Analysis of the influencing factors of vault after the implantation of posterior chamber-phakic refractive lens for patients with super high myopia / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the influencing factors of vault after the posterior chamber phakic refractive lens(PC-PRL)implantation for patients with super high myopia.METHODS: Retrospective case study. A total of 40 patients with super high myopia(77 eyes)who underwent PC-PRL implantation in the Haixiang Eye Hospital from January 2019 to January 2021 were selected. They were followed up for at least 2a, postoperative anterior segment parameters, such as the uncorrected visual acuity(UCVA), best corrected visual acuity(BCVA), central anterior chamber depth(ACD), anterior chamber volume(ACV), anterior chamber angle(ACA), lens thickness and vault were evaluated, and then the influencing factors of postoperative vault were analyzed.RESULTS: The UCVA and BCVA of the patients significantly improved after PC-PRL implantation(P<0.001). Average safety index(postoperative BCVA/preoperative BCVA)was 1.36±0.32, and average effective index(postoperative UCVA/preoperative BCVA)was 1.23±0.31 in 2a after surgery. The vault in 2a after surgery was correlated with preoperative ACD, ACV, ACA and lens thickness, and the preoperative ACV and lens thickness had significant impact on vault in 2a after surgery.CONCLUSIONS: The PC-PRL implantation is safe and effective in super high myopia, and it can significantly improve visual acuity. Furthermore, preoperative ACV and lens thickness are important influencing factors of postoperative vault.

The effect of different thickness scleral lens on corneal parameters in eyes with keratoconus

Purpose: To investigate the impact of different?thickness scleral lenses (SLs) on corneal thickness, curvature, and fluid reservoir thickness in keratoconic eyes. Methods: Schiempflug imaging and AS?OCT was captured before and immediately following 6 h of SL wear. Different?thickness lenses were used while keeping the other parameters the same. The timing of the measurement for day 1 and day 2 was matched to allow for the control of the confounding influence of diurnal variation. Results: Immediately after 6 h of lens wear, no statistically significant difference (P > 0.05) was noted in corneal edema in any region and quadrants between thin? and thick?lens wearers. The calculated percentage of corneal edema was also within the range of overnight closed eye physiological swelling. Pentacam measured higher central corneal thickness compared to AS?OCT in both baselines and after 6 h of lens wear. The current investigation reported minimal but not statistically significant (P > 0.05) flattening in anterior and steepening in posterior curvature parameters in both thin and thick SLs. The mean reduction in the fluid reservoir thickness was 80.00 ± 3.99 and 79.36 ± 3.84 microns after 6 h of thin? and thick?lens wear, respectively, which was not statistically significant (P > 0.05). A statistically significant positive correlation (r = 0.67, P = 0.02) was found between lens thickness and change in anterior steep k with thick?lens wear. Conclusion: Central lens thickness of 200–400 ?m did not cause any significant change in corneal curvature and fluid reservoir thickness and did not induce clinically significant corneal edema after short?term SL wear.

A comparison of lens parameters in patients with various subtypes of primary angle-closure disease and the normal population: A prospective study

Purpose: To assess the role of lens parameters in the detection and progression of primary angle-closure disease (PACD) by combining A-scan and A-scan optical coherence tomography (AS-OCT) parameters. Methods: A cross-sectional study was conducted in a tertiary health-care center in eastern India. A total of 91 study subjects including cases and controls were included in the study. The parameters studied were lens thickness (LT), lens axial factor (LAF), relative lens position (RLP), and lens vault (LV). Anterior chamber depth (ACD) and axial length (AL) were also analyzed using A-scan. Results: The LT was significantly more in all subtypes of PACD (from 4.24 ± 0.84 to 5.02 ± 0.18 mm) than in controls (4.04 ± 0.46 mm; P < 0.01). Similarly, LAF was significantly less among all subtypes of PACD compared to controls (P < 0.001). The RLP, calculated using the formula (ACD + 0.5 LT)/AL × 10, showed no significant difference (P > 0.05) between various study groups. The LV in acute angle-closure glaucoma (AcCG) patients was significantly higher compared to the control population (P < 0.01). Ocular parameters like ACD decreased, whereas LT and LAF increased from normal through primary angle closure (PAC) to primary angle-closure glaucoma (PACG). Logistic regression analysis found a significant association between a decrease in ACD and an increased risk of PACG (P-value was 0.0001) and an increase in LT and LAF with increased risk of PACG (P = 0.040 and P = 0.006, respectively). Conclusion: Inclusion of lens parameter assessment in the workup of a patient with PACD helps in detection and close monitoring of the progression from suspected to disease state.

Lowering of intraocular pressure after phacoemulsification in primary open-angle and angle-closure glaucoma: Correlation with lens thickness

Purpose: To assess anterior chamber configuration changes during phacoemulsification in primary angle?closure suspect (PACS/PAC) and primary open?angle glaucoma (POAG). Methods: Prospective observational comparative study of anterior segment optical coherence tomography (AS?OCT) findings before and after phacoemulsification on three groups of patients (PACS/PAC, POAG, and controls). Data were collected over a period of 9 months. Main outcome measures included mean change in anterior chamber depth (ACD), angle opening distance (AOD), and trabecular iris space area (TISA). Results: 153 patients (51 PACS/PAC, 51 POAG, and 51 controls) were included in the study. Change in all parameters (ACD, AOD at 500 um, and AOD at 750 um) between the groups demonstrated a greater change in PACS/PAC as compared to POAG and controls. AOD at 750 ?m in the temporal quadrant, which has been considered to be having the highest correlation or best representation of the angle, increased in all groups after phacoemulsification (463.59 ± 10.99 vs. 656.27 ± 9.73 mm in PACS; 521.29 ± 16.36 vs. 674.37 ± 8.72 mm in POAG; 549.27 ± 12.40 vs. 702.82 ± 13.04 mm in controls, (P < 0.001). After phacoemulsification, intraocular pressure (IOP) decreased by 2.75 ± 1.17 mm Hg in PACS/PAC (P < 0.001), 2.14 ± 1.33 mm Hg in POAG and 1.90 ± 1.25 mm Hg in controls and it was statistically significant in the PACS group compared to control (P < 0.001). Conclusion: Phacoemulsification with intraocular lens implantation is associated with increase in the ACD and angle parameters and a corresponding decrease in IOP. Findings were more pronounced in PACS/PAC suggesting early phacoemulsification may be a treatment option in this group

Changes and significance of refractive and lens regulation parameters in children with retinopathy of prematurity / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To investigate the clinical significance of changes of refractive and lenticular accommodation parameters in children with myopia of retinopathy of prematurity(ROP).<p>METHODS: A retrospective study was conducted in 98(192 eyes)1-6 year-old children with ROP who recovered spontaneously without treatment during outpatient follow-up between October 2018 and September 2019. According to the refractive screening results, the subjects were divided into myopia group(41 cases with 80 affected eyes)and non-myopia group(57 cases with 112 affected eyes). Meanwhile, 40 emmetropic premature infants(80 eyes)of the same age and without ROP were selected as the control group. Refractive parameters \〖spherical equivalent(SE), corneal curvature(CR), axial length(AL), anterior chamber depth(ACD), vitreous depth(VITR), lens thickness(LT)\〗 and lenticular accommodation parameters(SE and LT before and after mydriasis and their change values)in different groups were compared. Refractive parameters in myopic children with ROP in different age groups were analyzed, and the relationship among SE, refractive parameters and lens adjustment parameters in preschool myopic children with ROP was discussed.<p>RESULTS: SE and LT of myopia group(-3.95±1.31D, 4.21±0.34mm)were higher/larger than those of non-myopia group(1.32±0.36D, 4.08±0.21mm)and control group(1.39±0.42D, 3.71±0.41mm), while ACD(2.42±0.39mm)was lower than that of non-myopia group(2.61±0.24mm)or control group(3.11±0.32mm). Besides, LT of non-myopia group was larger than control group, and ACD was lower than control group(all <i>P</i><0.001). SE of myopia group before and after mydriasis(-3.95±1.31, -3.02±0.97D)were higher than those of non-myopia group(1.32±0.36, 2.67±0.81D)or control group(1.39±0.42, 2.61±0.76D). and the difference value of SE(0.93±0.30D)was lower than that of non-myopia group(1.31±0.31D)or control group(1.25±0.19D)(<i>P</i><0.001). LT before and after mydriasis(4.21±0.34, 3.95±0.22mm)were larger than those of non-myopia group(4.08±0.21, 3.71±0.37mm)or control group(3.71±0.41, 3.35±0.16mm), and the difference value of LT(0.26±0.08mm)was lower than non-myopia group(0.37±0.12mm)or control group(0.36±0.11mm). Moreover, LT of non-myopia group before and after mydriasis were larger than those of control group(all <i>P</i><0.001). For subjects under 3 years old, SE, CR and LT of myopia group were higher and ACD was lower than those of non-myopia group. For subjects between 3 and 6 years old, SE and LT of myopia group were higher than those of non-myopia group(all <i>P</i><0.05). SE was positively correlated with CR and LT in myopic children with ROP under 3 years old, but it was negatively correlated with the difference value of LT before and after mydriasis(<i>P</i><0.05); SE was positively correlated with LT in myopic children with ROP between 3 and 6 years old, but was negatively correlated with the difference value of LT before and after mydriasis(<i>P</i><0.05).<p>CONCLUSION: Refractive changes of preschool myopic children with ROP are characterized by lens thickening and shallow anterior chamber. Patients under 3 years old are accompanied by steep CR, and lens thickening appears after the age of three. CR is related to the occurrence of myopia of ROP in children under 3 years old. LT and lenticular accommodation are leading factors for myopia of ROP in children between 1 and 6 years old.

Corneal parameters and their correlations with refractive error, axial length, anterior chamber depth and lens thickness in black South Africans / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To establish profiles of corneal diameter(CD), curvature(ACC), corneal central thickness(CCT)and investigate their correlations with refractive errors' spherical equivalent(SE), axial length(AL), anterior chamber depth(ACD)and crystalline lens thickness(LT)in black South Africans with healthy eyes. We also investigated the intercorrelation among the three corneal parameters.<p>METHODS:Eyes of six hundred subjects that included 305 males and 295 females(mean age: 28.15±13.1y, range: 10-66y)underwent a complete ophthalmic examination including refraction, slit lamp and ophthalmoscopy. CD and ACC were measured using the Oculus Keratograph 4(OCULUS Optikgeräte GmbH), and the CCT was measured with the iVue-100(Optovue, Inc.)optical coherence tomography. Refractive errors were assessed with the Nidek AR-310A auto-refractor and then subjective refraction. The AL, ACD and LT were measured with the Nidek US-500 A-scan ultrasound device. <p>RESULTS:There are no statistically significant between the parameters of the right and left eyes assessed, and therefore only the results of the right eyes are presented here. The mean corneal parameter values were: CD=11.77±0.32 mm(range=10.30-13.70 mm), ACC=7.88±0.29 mm(range=7.13-8.88 mm)and CCT=493.05±33.2 μm(range=412-590 μm). CD did not correlate with SE(r=0.05, <i>P</i>=0.24). However, CD was correlated significantly with AL(<i>r</i>=0.58, <i>P</i>=0.00)and ACD(<i>r</i>=0.63, <i>P</i>=0.00)but inversely correlated with LT(<i>r</i>=-0.40, <i>P</i>=0.00). There was no significant correlations between ACC and SE(<i>r</i>=-0.03, <i>P</i>=0.48). ACC correlated positively with AL(<i>r</i>=0.40, <i>P</i>=0.00). There were no significant correlations between ACC and ACD(<i>r</i>=0.04, <i>P</i>=0.56), and LT(<i>r</i>=-0.03, <i>P</i>=0.88). Also, there was no correlation between CCT and other ocular dimensions assessed. However, correlations among corneal parameters showed that CD correlated with ACC(<i>r</i>=0.71, <i>P</i>=0.00)and CCT(<i>r</i>=-0.68, <i>P</i>=0.00).<p>CONCLUSION:While CD correlated with AL, ACD and LT, the ACC correlated with AL. CCT did not correlate with any of the metrics studied here, suggesting that it is an independent factor unrelated to other ocular dimensions. Among corneal parameters, CD correlated with ACC and CCT.

Comparison in lens thickness and anterior chamber of early and intumescent stages of cataract by CASIA SS-1000 anterior segment optical coherence tomography / 中华实验眼科杂志

Background With the progression of cortical cataract,the lens thickness and anterior chamber will change and may have significant influences on the structure and function of the eyes.A special measurement is needed to observe the anterior and posterior surface of lens and detailed angle structure,and to quantify these changes.Ohjective This study was to compare the lens thickness and angle structures by CASIA SS-1000 anterior segment optical coherence tomography (AS-OCT) in early and intumescent stage of cataract and quantify the ocular anatomical differences.Methods An observational study was performed.Fifty cortical cataract patients (87 eyes) of the early stage or the intumescent stage in the ophthalmology outpatient clinic of Daping Hospital from October 16 to October 30,2015 were continuously enrolled in this research.The eyes were assigned to the early stage group (28 patients 44 eyes) and the intumescent stage group (22 patients 43 eyes) according to the slit lamp examination results.The average age was (56.46 ± 12.90) years in the early stage group and (70.95 ± 8.81) years in the intumescent stage group.With the use of CASIA SS-1000 AS-OCT measurements,lens thickness,angle opening distance (AOD),angle recess area (ARA),trabecular-iris space area (TISA),trabecular-iris angle (TIA) and anterior chamber depth (ACD) were measured and compared between the two groups.Results Lens thickness was (4.438±0.487) mm in the early stage group and (5.094±0.451)mm in the intumescent stage group,with an average increase of (0.656±0.101) mm,showing a significant difference between the two groups (t =-6.513,P =0.000).ACD in the early stage group was (2.966±0.326)mm and (2.534±0.376)mm in the intumescent stage group,with an average decrease of (0.432±0.075)mm,showing a significant difference between the two groups (t =5.730,P =0.000).AOD500,AOD750,ARA500,ARA750,TISA500,TISA750,TIA500 and TIA750 were all lower in the intumescent stage group than those in the early stage group,with significant differences between the two groups (all at P=0.000).Conclusions The lens was thicker,ACD was shallower and anterior angle was narrower in the intumescent stage than those in the early stage of cortical cataract patients.SS-1000 AS-OCT is efficiency with high definition,and is supposed to have promising prospect of clinical application.

Analysis of related parameters of ocular biometric values in children and adolescents / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To measure ocular biometric values with sexual and age and determine the relationship between the differences using the Lenstar 900.METHODS:Totally 413 myopes 826 eyes,200 males (400 eyes) and 213 females (426 eyes),were enrolled in this study and were divided into 3 groups:Group Ⅰ (＜ 5 years),Group Ⅱ (5-10 years),Group Ⅲ (＞10 years).Central corneal thickness (CCT),anterior chamber depth (ACD),lens thickness (LT),axial length (AL),white-to-white distance (WWD) and pupil diameter (PD) were measured by Lenstar 900.The differences between age groups and gender groups were compared using the LSD and SNKk methods in variance analysis.Pearson correlation coefficient to assess AL,CCT,ACD,LT,WWD,PD in children and adolescents.RESULTS:There were significant difference in CCT between ages groups (P＜0.05) which increased with the age.There were significant differences both in ACD and AL between sexual groups.With analysis of Person,CCT showed a significantly positive correlation with WWD and PD(r=0.208,0.167;P＜0.05) and ACD showed a significantly positive correlation with AL,WWD,PD(r=0.620,0.238,0.192;P＜0.05).LT showed a significantly negative correlation with ACD,AL and WWD (r=-0.271,-0.186,-0.227;P＜0.05).WWD showed a significantly positive correlation with PD (r=0.273,P＜0.05).CONCLUSION:CCT has gradually thickening trend with ages.Men are more than women in ACD and AL.CCT shows positive correlation with WWD and PD and ACD shows positive correlation with AL,WND,PD.LT shows negative correlation with ACD,AL and WWD.WWD showed positive correlation with PD.

Research progress on the measurement of human lens thickness in vivo / 国际眼科杂志(Guoji Yanke Zazhi)

The precise measurement in lens thickness in vivo, provides great application value for intraocular accommodation and ametropia development mechanism research.And it has great clinical significance for the diagnosis and treatment of glaucoma and cataract.Currently, many ultrasonic methods and optical methods are used in measuring lens thickness.The measurement principles, advantages, disadvantages and the accuracy of the instruments are summarized in this paper.Among these methods, Orbscan II, Pentacam, Lenstar and AS-OCT can be used to measure lens thickness instead of A-scan.More important is the fact that UL-OCT can dynamically monitor the change of the lens thickness with intraocular accommodation.Choosing an instrument with higher measuring accuracy to examine the lens thickness, can provide more accurate and convincing lens thickness data for clinical and scientific research.

The difference of lens thickness measured by immersion A-scan ultrasound versus Lenstar optical biometry in various types of cataract eyes and its clinical significance / 中华实验眼科杂志

Background Cataract is the main cause of global blindness,and surgery is the main method for the treatment of cataract,so precise preoperative parameters have an important significance for improving postoperative visual quality.Objective This study was to analyze the difference of lens thickness (LT) measured by immersion A-scan ultrasound versus optical biometry and consistency of these two methods in measuring the LT for different types of cataract eyes,and to investigate whether A-scan ultrasound for the LT measurement needs to correct the ultrasound speed parameter.Methods A reliability evaluation of diagnosis test was designed.The LT was measured on 143 cataract eyes using immersion A-scan ultrasound and Lenstar optical biometry in Tianjin Eye Hospital from September 2013 to May 2014.The eyes were assigned to nuclear cataract group (60 eyes of 50 patients),posterior subcapsular cataract group (40 eyes of 40 patients) and cortical cataract group (43 eyes of 43 patients) based on the types of cataract,and the hardness of nucleus was grade II in 20 eyes of 14 patients,grade Ⅲ in 20 eyes of 17 patients and grade Ⅳ in 20 eyes of 19 patients.The outcomes measured by immersion A-scan ultrasound versus Lenstar optical biometry were compared with paired t test,and the consistency between the two devices was analyzed by Bland-Altman agreement plot.This study complied with Helsinki declaration,and written informed consent was obtained from each patient prior to any examination.Results The mean LT value was (4.85± 0.39) mm from the immersion A-scan ultrasound and (4.74 ±0.37)mm from the Lenstar optical biometry,with a significant difference between the two devices (t =3.020,P =0.004).No significant differences were found in the LT values of the posterior subcapsular cataractous eyes and cortical cataractous eyes between the two devices (t=1.015,P =0.316;t =1.275,P =0.209).The LT values by immersion A-scan ultrasound were significantly higher in grade Ⅱ,Ⅲ and Ⅳ nuclear cataractous eyes than those by Lenstar optical biometry (t=2.175,2.378,2.383,all at P＜0.05).The outcome showed a good consistency in the posterior subcapsular cataractous eyes between the two measuring methods,with the 95％ limitation of agreement (LoA) from-0.21 to 0.18 mm.However,there were poor consistencies between the two measuring methods in the nuclear and cortical cataractous eyes,with the 95％ LoA from-0.64 to 0.43 mm and from-0.50 to 0.41 mm,respectively.Poor consistencies also were seen in grade Ⅱ,Ⅲ,Ⅳ nuclear cataractous eyes between the two measuring methods,and the 95％ LoA were-0.31 to 0.22 mm,-0.32 to 0.24mm and-1.09 to 0.62 mm,respectively.Conclusions There are differences in measuring LT of different types of cataractous eyes between immersion A-scan ultrasound and Lenstar optical biometry.The measuring values are higher by immersion A-scan ultrasound than those by Lenstar optical biometry,suggesting that the measurement of immersion A-scan ultrasound for LT of different types and nuclear hardness of cataractous eyes should correct the ultrasound speed parameters.

Influence of Biometric Variables on Refractive Outcomes after Cataract Surgery in Angle-closure Glaucoma Patients

PURPOSE: To evaluate the influence of biometric variables on refractive outcomes after cataract surgery in angle-closure glaucoma (ACG) patients. METHODS: In this case-control study, 42 ACG patients, 40 open-angle glaucoma (OAG) patients, and 35 controls without glaucoma who had undergone conventional cataract surgery were enrolled consecutively. Electronic medical records, including preoperative biometric variables (keratometric diopter, axial length, anterior chamber depth, and lens thickness), the refractive change (RC), and the absolute value of refractive change (ARC) were reviewed. RESULTS: In the control and OAG patients, the anterior chamber depth was negatively correlated with the ARC (r = -0.344, p = 0.043 and r = -0.431, p = 0.006, respectively), whereas there was no correlation in the ACG patients. Lens thickness was positively correlated with the RC, but not with the ARC, in the control and OAG groups (r = 0.391, p = 0.020 and r = 0.501, p = 0.001, respectively). In contrast, lens thickness in the ACG group was not correlated with the RC but was positively correlated with the ARC (r = 0.331, p = 0.032). CONCLUSIONS: In contrast with the anterior chamber depth, preoperatively measured lens thickness may be a useful predictor of the direction of the RC after cataract surgery in control and OAG patients. However, in ACG patients, a thicker lens was correlated with a larger RC, regardless of the direction of the shift (hyperopic or myopic).

Analysis on biometric measurements of Lenstar 900 in difference degrees of axial myopia / 国际眼科杂志(Guoji Yanke Zazhi)

AlM: To measure ocular biometric values with the degree of axial myopia and determine the relationship between the differences using the Lenstar 900. METHODS:Totally 413 myopes (826 eyes) were enrolled in this study and were divided into 3 groups: low myopia (myopia 6. 00 diopters, 222 eyes ). Central corneal thickness ( CCT ) , aqueous depth ( AD ) , lens thickness (LT), axial length (AL) were measured by Lenstar 900. The parameters were tested using analysis of variance and the relations among SE, AL, LT were analyzed. RESULTS: There were significant difference both in AL (F=206.16, P CONCLUSlON: Along with the diopters increasing in myopia, the axial length and aqueous depth continue to increase. Spherical equivalent ( SE) shows a significantly positive correlation with AD. AL shows positive correlation with SE, AD and CCT and negative correlation with LT. LT shows a significantly negative correlation with AD.

Growth of the human lens in the Indian adult population: Preliminary observations.

Context: The eye lens grows throughout life by the addition of new cells inside the surrounding capsule. How this growth affects the properties of the lens is essential for understanding disorders such as cataract and presbyopia. Aims: To examine growth of the human lens in the Indian population and compare this with the growth in Western populations by measuring in vitro dimensions together with wet and dry weights. Settings and Design: The study was conducted at the research wing of a tertiary eye care center in South India and the study design was prospective. Materials and Methods: Lenses were removed from eye bank eyes and their dimensions measured with a digital caliper. They were then carefully blotted dry and weighed before being placed in 5% buffered formalin. After 1 week fixation, the lenses were dried at 80 °C until constant weight was achieved. The constant weight was noted as the dry weight of the lens. Statistical Analysis Used: Lens parameters were analyzed as a function of age using linear and logarithmic regression methods. Results: Data were obtained for 251 lenses, aged 16–93 years, within a median postmortem time of 22 h. Both wet and dry weights increased linearly at 1.24 and 0.44 mg/year, respectively, throughout adult life. The dimensions also increased continuously throughout this time. Conclusions: Over the age range examined, lens growth in the Indian population is very similar to that in Western populations.

The Effect of Lens Thickness to Anterior Chamber Depth on the Vault after ICL Implantation

PURPOSE: To evaluate the crystalline lens thickness/anterior chamber depth (CLT/ACD) ratio as a preoperative factor that affects the vault after implantable contact lens (ICL) implantation. METHODS: A total of 130 eyes of 130 patients who received bilateral ICL implantation were included in the present study. The preoperative CLT/ACD ratio was analyzed to determine if the patients had any correlation with postoperative vault by Visante optical coherence tomography (OCT). RESULTS: The mean vault was 0.58 mm +/- 0.23 at postoperative 2 months. Eight eyes (6.15%) had low vault, 93 eyes (71.53%) had ideal vault and 29 eyes (29.31%) had high vault. The CLT/ACD ratios were 1.04 mm +/- 0.11, 0.96 mm +/- 0.09 and 0.90 mm +/- 0.09 in the low vault group, ideal vault group and high vault group, respectively (p < 0.01). The CLT/ACD ratio showed statistically significant correlations with postoperative vault in univariate analysis (r = -0.4718; p < 0.01) and in multivariate analysis (p < 0.01). CONCLUSIONS: Vaults after ICL implantation have a negative correlation with the preoperative CLT/ACD ratio. The results from the present study may improve the prediction of postoperative vault after ICL implantation.

Retrospective analysis of the risk factors for developing phacomorphic glaucoma.

Aim: To determine the risk factors for developing phacomorphic glaucoma in eyes with mature cataracts. Materials and Methods: This is a case-control study comprising of 90 eyes with phacomorphic glaucoma and 90 age- and sex-matched control eyes with mature cataracts without phacomorphic glaucoma. Patients with pre-existing glaucoma, previous intraocular surgery and /or absence of documented axial lengths were excluded from this study. Binary logistic regression analysis of the variables, axial length and anterior chamber depth, was performed. Anterior chamber depth of the contralateral eye was used as a proxy measure of the pre-phacomorphic state in the eye with phacomorphic glaucoma as majority of them first presented to our center during the phacomorphic attack without prior measurements of the pre-phacomorphic ACD or lens thickness; therefore, their anterior chamber depth would not be representative of their pre-phacomorphic state. Axial length of 23.7 mm was selected as a cut-off for dichotomized logistic regression based on the local population mean from published demographic data. Results: The mean age was 73.1 ± 10.2 years. All phacomorphic and control eyes were ethnic Chinese. The mean presenting intraocular pressures were 49.5 ± 11.8 mmHg and 16.7 ± 1.7 mmHg in the phacomorphic and control eyes respectively (P< 0.0001), whilst the median Snellen best corrected visual acuity were light perception and hand movement in the phacomorphic and control eyes respectively. Eyes with phacomorphic glaucoma had shorter axial length of 23.1 ± 0.9 mm median when compared with that of control eyes, 23.7 ± 1.5 mm (P = 0.0006). Eyes with AL ≤ 23.7 mm were 4.3 times as likely to develop phacomorphic glaucoma when compared with AL > 23.7 mm (P = 0.003). Conclusion: Axial length less than ≤ 23.7 mm was a risk factor for developing phacomorphic glaucoma. Eyes with AL shorter than the population mean were 4.3 times as likely to develop phacomorphic glaucoma compared with eyes with longer than average AL. In an area where phacomorphic glaucoma is prevalent and medical resources are limited, patients with AL shorter than their population mean may be considered for earlier elective cataract extraction as a preventive measure.

Correlation between ocular parameters and amplitude of accommodation.

Aim: To study the relationship between ocular parameters and amplitude of accommodation (AA) in the peri-presbyopic age group (35–50 years). Materials and Methods: Three hundred and sixteen right eyes of consecutive patients in the age group 35–50 years, who attended our outpatient clinic, were studied. Emmetropes, hypermetropes and myopes with best-corrected visual acuity of 20/20, J1 in both eyes were included. The AA was calculated by measuring the near point of accommodation. The axial length (AL), central anterior chamber depth (CACD) and lens thickness (LT) were also measured. Results: There was moderate correlation (Pearson’s correlation coefficient r = 0.56) between AL and AA as well as between CACD and AA (r = 0.53) in myopes in the age group 35–39 years. In the other age groups and the groups taken as a whole, there was no correlation. In hypermetropes and emmetropes, there was no correlation between AA and the above ocular parameters. No significant correlation existed between LT and AA across different age groups and refractive errors. Conclusion: There was no significant correlation between AA and ocular parameters like anterior chamber depth, AL and LT.

Correlation between Lens Thickness and Anterior Chamber Depth after Cataract Operation

The accuracy of intraocular lens power calculation in cataract surgery depends on three factor :accuracy of the biometric data[axial length, corneal power, predicted pseudophakic anterior chamber depth], accuracy of manufacturer of IOL power quality, and accuracy of the IOL power formulas usedto obtain desired lens power. We retrospectively analyzed 27 patients[40 eyes] who had taken 3.2 millimeterscleral tunnel incision and been implanted with Silicone IOL. We evaluated the correlation between pseudophakic anterior chamber depth and preoperative lens thickness. And, we calculated the ratio of anterior and posterior distance from the central point on the presumption that there is the central point remaining constant despite of thickening of lens. The preoperative mean lens thickness was 4.47 +/-0 .4 9 mm. The change of anterior chamber depth was significantly increased according to the lens thickness at postoperaitve 3months[r=0.57, p<0.01]. The mean ratio of anterior and posterior distance from central point was 0.29:0.71. This result suggests that the postoperative anatomical center of IOL will change more posterior as increasing preoperative lens thickness. And we concluded that we would more exactly predict postoperative pseudophakic anterior chamber depth considering the preoperative lens thickness if the ratio of lens thickening was constant.

The Relationship of the Lens Density with the Lens Thickness and the Anterior Chamber Depth

To investigate the relationship of the density change of lens nucleus and cortex with anterior chamber depth and lens thickness, we measured the anterior chamber depth, density and length of lens nucleus and cortex of 312 eyes with a Scheimpflug camera. The mean values of density of lens nucleus and cortex were 108.45+/-46.33CCT and 27.74+/-13.76CCT, respectively. The mean values of the thickness for both were 2.85+/-0.54mm and 1.29+/-0.46mm, respectively. The mean value of anterior chamber depth was 2.93+/-0.49mm. The densities of lens nucleus and cortex were increased significantly with aging, but lens thickness and anterior chamber depth were decreased. The value of anterior chamber depth changes and lens thickness changes were more rapid especially in the 5th and 7th decades compared with other groups(P<0.01), and more rapaid in the density group(100~150CCT) than other group in changing densities(P<0.05), and they were highly correlated with anterior cortex, posterior cortex, nucleus in order at each portion of lens. Both anterior chamber depth changes and lens thickness changes were more rapid in the lens cortex than those in the lens nucleus.

Biometric Measurements in Acute Angle Closure Glaucoma

Biometric measurements were made by ultrasonography in 30 eyes of 25 patients (18 Women and 7 men, mean 67.9 yrs) with acute angle closure glaucoma against 52 eyes of 26 age-matched normal persons (20 women and 6 men, mean 65.1 yrs) in order to analyze an affecting factor of lens in acute primary angle closure glaucoma. The 26 eyes of 30 patients' eyes was subjects older than 60 years of age and mean intraocular pressure was 57.06 +/- 16.764 mmHg The mean anterior chamber depth of these patients (1.895 +/- 0.193 mm) was 0.95mm shallower than one of controls (2.840 +/- 0.324 mm). The mean lens thickness was slgmtlCantly larger tor pal1ents (patients 5.024 +/- 0.498 mm, controls 4.168 +/- 0.524 mm, p=0.001). The mean axial length was 0.6 mm shorter for patients (patients 22.385 +/- 0.840 mm, controls 22.985 +/- 0.838 mm, p<0.01). The relative lens position was significantly smaller for patients (patients 0.194, controls 0.214, p=0.0001), but relative posterior capsule position was similar in two groups. The study suggested that the increased thickness and forward positioning of lens was one of important factors for anterior chamber angle closure in primary angle closure glaucoma.

Biometric analysis of anterior segments of the eye with Scheimpflug Camera according to the type of cataract

We measured the lens thickness and anterior chamber depth on 214 eyes (162 cataract eyes, 52 normal control eyes) using the EAS-1000 Scheimpflug camera. And the results was compared with measurement of A-scan ultrasonography in 49 cataract eyes. The thickness of cataract lens, especially in anterior subcapsular opacities in over 61 years old was significantly thin rather than control lens (p0.05). Lens thickness was increased with age by an annual rate of 0.0l5mm in monnal eyes (p