Changes of choroidal structure in children with hyperopic amblyopia observed by EDI-OCT technique / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To compare the differences in choroidal structure between hyperopic amblyopia and normal children of the same age by the enhanced depth imaging optical coherence tomography(EDI-OCT)technique.METHODS: There were 35 cases in 50 eyes of children with hyperopic amblyopia visiting our hospital in January 2021 to December 2021 selected in the amblyopic group, and 30 cases in 51 eyes of healthy children who matched general data in the same period were selected in the control group. EDI-OCT examination was performed to measure the choroidal thickness(CT). After image processing, the total choroidal area(TCA), luminal area(LA), stromal area(SA)and choroidal vascularity index(CVI)were obtained.RESULTS: TCA(except inferior quadrant), SA(except inferior quadrant of the outer ring), LA and CT(except inferior and temporal quadrant )in the amblyopic group of each area were significantly larger than that in the control group(P<0.05), and there was no significant difference in CVI between the two groups except the temporal quadrant of the outer ring(P>0.05). There was no significant difference in CT for all degrees of hyperopic amblyopia, with the exception of the nasal quadrant(P>0.05).CONCLUSION: Hyperopic amblyopia is accompanied with abnormal choroidal structure. As the degree of hyperopia increases, TCA, LA and SA exhibit increasing trends. The changes in choroidal structure are presumed to be related to hyperopic amblyopia.

Effect on visual parameters in myopic children wearing spectacle lens designed to reduce peripheral hyperopic defocus / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To study the efficacy of AMSPL on myopia control, and confirm the security of wearing AMSPL, through comparing the impacts on visual parameters between myopic children wearing spectacle lens designed to reduce peripheral hyperopic defocus(AMSPL)and myopic children wearing the standard design control lens(SPL).<p>METHODS: Totally 50 children aged 8 to 14 years wearing spectacle lens designed to reduce peripheral hyperopic defocus(AMSPL)were collected into the AMSPL group, and other 50 children in the same age, the same degree of myopia and the same glasses time wearing standard design control lens(SPL)were selected into normal control group randomly(SPL group). We reviewed their documents and exam all patients. The examination include intraocular pressure, refraction under cycloplegia, distant strabismus and near strabismus, AC/A ratio. <p>RESULTS: The children wearing spectacle lens designed to reduce peripheral hyperopic defocus(AMSPL)had lower feeling of comfort than SPL group, mainly in peripheral vision confused, but no difference between them 1mo later. The AMSPL group's average growth of refractive error is -0.62±0.50D, the SPL group's average growth of refractive error is -0.77±0.48D(<i>P</i>=0.072). In myopic children aged 8 to 10 years, the AMSPL group's average development of refractive error is -0.71±0.41D, lower than the SPL group that of -1.05±0.39D, the difference was significant(<i>t</i>=2.164, <i>P</i>=0.041). Between the two groups, there was no significant difference(<i>P</i>>0.05)in visual parameters of distant strabismus, near strabismus, AC/A ratio.<p>CONCLUSION: Wearing spectacle lens designed to reduce peripheral hyperopic defocus(AMSPL)can delay the progression of myopia to a certain extent, especially for myopic children aged 8 to 10 years. It suggests that wearing AMSPL has the same safety with SPL for myopic children.

A Longitudinal Change of Spherical Equivalent in Anisometropic Children

PURPOSE: To demonstrate longitudinal refractive changes of anisometropia children. METHODS: This retrospective study included patients (or children) with anisometropia ≥ 1 diopters (D) for 5 years who visited our hospital between January 2013 and December 2014 with patients having annual refraction test data from 5-years-old to 10-years-old. RESULTS: A total of 37 children satisfied the inclusion criteria. Twenty-one children had hyperopic anisometropia and 16 children had myopic anisometropia. All hyperopic anisometropia and 12 myopic anisometropia children who had unilateral amblyopia were treated with occlusion therapy. The mean anisometropia at 5 years of age was 3.02 D and in the 37 children, the final degree of anisometropia was not significantly different between the 5-year-old and 10-year-old patients. In the high anisometropia and low anisometropia groups and in the myopia and hyperopia groups, the final degree of anisometropia was not significantly different at 5 years of age versus 10 years of age. CONCLUSIONS: In patients with anisometropia, spherical equivalent values did not show a significant difference when comparing 5-year-old versus 10-year-old patients and changes in the spherical equivalent values of eyes from both groups progressed to the same degree even if there was anisometropia in myopic and hyperopic patients.

Cálculo del lente intraocular en hipermétropes con antecedente de cirugía refractiva láser / Intraocular lens calculation in hypermetropic patients with history of refractive laser surgery

Objetivo: comparar las queratometrías obtenidas por el Pentacam en ojos hipermétropes operados con excímer láser y la obtenida a través del método de la historia clínica, en el Instituto Cubano de Oftalmología Ramón Pando Ferrer, de marzo a junio del año 2011. Métodos: se realizó un estudio en 50 ojos de 25 pacientes hipermétropes operados con la técnica Lasik, donde se calculó la queratometría promedio mediante el método de la historia clínica y se comparó con los valores de la queratometría brindados por el Pentacam: valor del ápex corneal de los mapas a color (valor queratométrico total central) y la lectura queratométrica equivalente, así como el True Net Power (queratométrico total a 3,0 mm) y las equivalent K reading del programa Holladay Report. Se calculó la queratometría preoperatoria media de la historia clínica y se comparó con la queratometría preoperatoria estimada aportada por el Pentacam. El análisis estadístico se realizó con la Prueba T para datos pareados, utilizando una significación del 95 por ciento. Resultados: los valores entre los que no hubo diferencias estadísticas con respecto al obtenido por el método de la historia clínica fueron el equivalent K reading power y las lecturas queratométricas equivalentes a 3, 4 y 4,5 de diámetro. La más exacta fue la de 4,5 mm. Las queratometrías preoperatorias no mostraron diferencias. Conclusiones: el Pentacam aporta poderes corneales que no difirieren estadísticamente de los obtenidos por el método de historia clínica en ojos hipermétropes que tengan cirugía previa con excímer láser(AU)

Objective: to compare the keratometries estimated by Pentacan in hypermetropic eyes operated on with laser Excimer and those measured through the medical history method at Ramón Pando Ferrer Cuban Institute of Ophthalmology from March to June, 2011. Methods: a study was performed in 50 eyes from 25 hypermetropic patients operated on by Lasik technique, where average keratometry was estimated by using the medical history method and then compared with the Pentacam-estimated keratometry values such as corneal apex value of the colour maps (total central keratometric value) and equivalent K-reading power as well as the the true net power (total keratometric value at 3.0 mm) and the equivalent keratometric readings of the Holladay Report program. The preoperative mean keratometry of the medical history was then estimated and compared with the preoperative keratometry estimated with Pentacam. The statistical analysis was performed by using the T Test for paired data, with 95 percent significance. Results: among the keratometric values which did not show statistical differences when compared with those of the medical history method were the equivalent K-reading power and the equivalent keratometric readings at 3, 4 and 4.5 mm diameters, being that of 4.5 mm the most accurate.There were no differences among the preoperative keratometries. Conclusion: Pentacam provides corneal power estimations that did not statistically differ from the ones obtained by the clinical history method in hypermetropic eyes which had previously undergone Excimer laser surgery(AU)

Contrast observation of the effect of frame mirror and corneal contact lens correction on the optical properties of the human eye / 中国生化药物杂志

Objective To explore the effect of the contrast frame mirror and the corneal contact lens correction on the optical properties of the human eye.Methods120 cases of myopia patients from 2014 September to September 2015 in our hospital for vision correction were randomly divided into two groups: control group, observation group wearing frame mirror, wearing contact lens, the optical properties of the eye were compared between the two groups.ResultsThe corrected visual acuity of observation group hadno significant difference compared with the control group;no significant difference in the values of refractive foveal contrast;foveal refractive value contrast in the two groups had no statistical difference;the observation group T30 degrees for peripheral refraction was (1.00±0.21) D, N30°peripheralrefraction was (0.34±0.08) D,were significantly lower than the control group (P<0.05).The good rate of observation group was significantly higher than the control group, the incidence of corneal complications was significantly lower than that of the control group (P<0.05).ConclusionThe frame and the corneal contact lens can be well corrected visual acuity, the corneal contact lens for the correction of certain peripheral hyperopic defocus has advantages, can effectively reduce the peripheral hyperopic defocus, delaying myopia, and improve the comfort and safety.

Curative effects of excimer laser corneal refractive surgery for hyperopic anisometropic amblyopia / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate curative effects of excimer laser corneal refractive surgery for adults or older adolescent with hyperopic anisometropic amblyopia.METHODS: From March 2014 to March 2016, we selected 26 cases 26 eyes of adults or older adolescent with hyperopic anisometropic amblyopia in our hospital.All eyes underwent laser in situ keratomileusis, observed for the uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), diopter and stereopsis.RESULTS: At the end of the follow-up, the patient`s spherical equivalent and anisometropia were 1.47±0.51D and 1.15±0.22D, were significantly lower than that before operation (P<0.05).At the end of the follow-up, the distance and near UCVA and BCVA were 0.26±0.13 and 0.23±0.09, 0.42±0.09 and 0.31±0.16, which were significantly higher than those before operation (P<0.05).At the end of follow-up, the visual function of the patients was significantly improved (P<0.05), the rate of postoperative visual function < 100 eyes was 23%.CONCLUSION: In adult or older adolescent with hyperopic anisometropic amblyopia, excimer laser corneal refractive surgery has a certain effect.

Clinical analysis of retinal nerve fiber layer thickness and macular fovea in hyperopia children with anisometropia amblyopia / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To analyze the clinical significance of axial length, diopter and retinal nerve fiber layer thickness in hyperopia children with anisometropia amblyopia. ·METHODS: From January 2015 to January 2017 in our hospital for treatment, 103 cases, all unilateral, were diagnosed as hyperopia anisometropia amblyopia. The eyes with amblyopia were as experimental group ( 103 eyes), another normal eye as control group (103 eyes). We took the detection with axial length, refraction, foveal thickness, corrected visual acuity, diopter and the average thickness of retinal nerve fiber layer. ·RESULTS: Differences in axial length and diopter and corrected visual acuity were statistically significant between the two groups (P0. 05). There was statistical significance difference on the foveal thickness (P0. 05 ). The positive correlation between diopter with nerve fiber layer thickness of foveal and around the optic disc were no statistically significant difference (P>0. 05). ·CONCLUSION:Retinal thickness of the fovea in the eye with hyperopic anisometropia amblyopia were thicker than those in normal eyes;the nerve fiber layer of around the optic disc was not significantly different between the amblyopic eyes and contralateral eyes. The refraction and axial length had no significant correlation with optic nerve fiber layer and macular foveal thickness.

Management of Complication after Hyperopic Laser-assisted in-situ Keratomileusis

PURPOSE: We present a case of a patient who underwent corneal refractive surgery to improve their corrected visual acuity due to a complication of hyperopic laser-assisted in-situ keratomileusis (LASIK). CASE SUMMARY: The patient complained of decreased vision after hyperopic LASIK surgery 12 years prior. The corrected distance visual acuity (CDVA) was 20/200 in the right eye and 20/32 in the left, with manifested refractions of +1.25 +2.00 × 90 and -0.25 +2.00 × 80, respectively. The patient had a with-the-rule astigmatism. The values of corneal and total spherical aberration, which can be determined as coefficients of the Zernike polynomials, were respectively -1.027 µm and -0.773 µm in the right eye and -0.965 µm and -0.881 µm in the left eye. Slit lamp biomicroscopy revealed no remarkable findings. We performed surface ablation surgery to flatten the central cornea of the patient's right eye. At 12 months after surgery, the CDVA of the patient's right eye was 20/30 and the negative corneal spherical aberration was reduced. CONCLUSIONS: Corneal refractive surgery to reduce negative corneal spherical aberration by flattening the central cornea is one of possible treatment options for the reduced corrected distance visual acuity after hyperopic LASIK.

Effect of Co-Implantation of a Capsular Tension Ring on Clinical Outcomes after Cataract Surgery with Monofocal Intraocular Lens Implantation

PURPOSE: The objective was to evaluate the effect of co-implantation of a preloaded capsular tension ring (CTR) and aberration-free monofocal intraocular lens (IOL) on clinical outcomes and visual quality after cataract surgery. MATERIALS AND METHODS: Patients who underwent cataract surgery were randomized into two groups that were implanted with a CTR and IOL (group 1, 26 eyes) or an IOL only (group 2, 26 eyes). At 1 and 3 months after surgery, visual acuity, refractive errors, refractive prediction errors, ocular aberrations, and modulation transfer function (MTF) were analyzed. At 3 months postoperatively, anterior chamber depth (ACD) and contrast sensitivity were evaluated. RESULTS: Group 1 showed greater hyperopic shift, which caused the refractive prediction error at 3 months after surgery to be significantly different between the two groups (p=0.049). Differences in ACD between the preoperative and postoperative periods tended to be greater in group 1 than in group 2. At 3 months postoperatively, internal MTF values at 20, 25, and 30 cycles per degree were significantly better in group 1 than in group 2 (p=0.034, 0.017, and 0.017, respectively). Contrast sensitivity showed comparable results at almost all spatial frequencies between the groups. CONCLUSION: Regarding visual acuity and quality, both groups showed comparable results. Co-implantation of a CTR and aberration-free monofocal IOL was associated with hyperopic refractive outcomes. Surgeons should consider the position of the IOL when planning co-implantation of a CTR and IOL.

Refractive Accommodative Esotropia: Duration between Wearing Hyperopic Glasses and Control of Esotropia within 8 PD

PURPOSE: To report clinical aspects of children diagnosed with refractive accommodative esotropia after wearing their first glasses to correct hyperopia accompanied with esodeviation. METHODS: The present study included 75 children followed up for at least 24 months. Age, spherical equivalent of refractive error, angle of deviation and presence of amblyopia were analyzed according to the duration between first wearing glasses and control of esotropia within 8 PD (2 months). RESULTS: The mean age was 4.48 +/- 2.08 years and mean follow-up was 50.17 months. Initial deviation angle without glasses was 25.43 +/- 10.07 PD at far, 27.72 +/- 11.45 PD at near, spherical equivalent was +4.86 +/- 2.41 D in right eyes, +5.05 +/- 1.06 D in left eyes and 8 of 75 patients (10.67%) had 2 months had less hyperopia (+4.02 D vs. 5.17 D), more severe esodeviation both at far (30.79 +/- 10.79 PD vs. 24.17 +/- 9.56 PD, p = 0.03) and at near distance (34.00 +/- 14.20 PD vs. 26.25 +/- 10.31 PD, p = 0.02) and higher initial amblyopia prevalence rates (71.5% vs. 47.5%). CONCLUSIONS: Several patients needed longer follow-up until esotropia was controlled within 8 PD after wearing hyperopic glasses considering the amount of hyperopia and angle of esodeviation.

Optical quality of hyperopic and myopic phakic intraocular lenses.

Aims: To assess and compare the optical quality of the myopic and hyperopic implantable collamer lens (ICL) from its wavefront aberrations for different powers and pupil diameters. Settings and Design: Prospective study. Material and Methods: The wavefront aberrations of two myopic (−3 and −6 diopters (D)) and two hyperopic V4b ICLs (+3 and +6D) were measured in vitro. To assess and compare the optical quality of different powers of ICLs, we analyzed the root mean square (RMS) of total higher order aberrations (HOAs), trefoil, coma, tetrafoil, secondary astigmatism, and spherical aberration at 3‑ and 4.5‑mm pupil. In addition, the point spread functions (PSFs) of each ICL evaluated were calculated from the wavefront aberrations at 3‑ and 4.5‑mm pupil. Statistical Analysis: A Student’s t‑test for unpaired data was used for comparison between myopic and hyperopic ICLs. Results: Myopic ICLs showed negative spherical aberration, in contrast hyperopic ICLs showed positive spherical aberration, which increases when the ICL power increases, due to the innate optical properties of the lens. All ICLs evaluated had negligible amounts of other aberrations. We did not find statistical significant differences in any Zernike coefficient RMS values analyzed between myopic and hyperopic ICLs at 3‑ and 4.5‑mm pupil (P > 0.05). Conclusions: Myopic and hyperopic ICLs provide good and comparable optical quality for low to moderate refractive error. The ICLs evaluated showed values of wavefront aberrations clinically negligible to affect the visual quality after implantation.

The Initial Factors Influencing Successful Final Stereoacuity in Refractive Accommodative Esotropia

PURPOSE: To evaluate the initial factors influencing successful final stereoacuity in patients with refractive accommodative esotropia. METHODS: The charts of 48 refractive accommodative esotropia patients 2 years of age or older andassessed using the Titmus stereoacuity test were retrospectively reviewed. Hyperopic refractive error on post-cycloplegic refraction, age at first glasses, stereoacuity after refractive correction and amblyopia were categorized and evaluated as the factors influencing final stereoacuity. RESULTS: The mean follow-up period was 43.51 +/- 30.02 months. The mean hypermetropia at the initial examination was 4.67 +/- 2.18 diopters (D), the mean age at first glasses was 48.09 +/- 20.22 months and the mean stereoacuity after refractive correction was 1243.75 +/- 1378.24 seconds of arc. The rates of successful stereoacuity at the final visit were 83.3% without amblyopia, 75.0% with mild amblyopia and 42.9% with moderate amblyopia which were statistically significant (p = 0.039). Hyperopic refractive error and age at first glasses were categorized as +1.0 to or =+5.0 D and 2 to or =6 years, respectively, and the rates of successful stereoacuity at the final visit were 83.3%, 66.7%, 61.9% (p = 0.362) and 71.4%, 75.0% and 54.5% (p = 0.334), respectively. CONCLUSIONS: The amblyopia at the initial examination was significantly associated with the outcome of stereoacuity at the final visit in patients with refractive accommodative esotropia.

Clinical Manifestation of Patients with Accommodative Esotropia for 10 Years

PURPOSE: To analyze the clinical features of patients who successfully discontinued correction with hyperopic glasses for refractive accommodative esotropia during a 10 year follow-up. METHODS: The authors of the present study analyzed 29 patients followed-up for a minimum of 10 years after diagnosis of accommodative esotropia. The patients were divided into 2 groups: patients who successfully discontinued correction with hyperopic glasses (10 patients, Group A), and patients who required constant use of hyperopic glasses (19 patients, Group B). The age at first visit, refractive error, deviated angle without correction, stereopsis, and follow-up duration were compared between the 2 groups. RESULTS: The mean age at first visit for all patients was 3.03 +/- 1.46 years, and the follow-up duration was 11.3 +/- 1.51 years. Patients in Group A discontinued the use of hyperopic glasses after 10.26 +/- 2.08 years. There were no statistical differences in mean age at first visit, deviated angle without correction, stereopsis, follow-up duration, or the amount of change in hyperopia. The initial amount of hyperopia in Group A was 3.81 +/- 1.54 D, significantly lower than the 5.12 +/- 1.37 D in Group B. CONCLUSIONS: After a 10 year follow-up of accommodative esotropia, 34% of the patients discontinued the use of hyperopic glasses, and the hyperopic amount at initial visit was statistically lower than that of patients who required constant use of hyperopic glasses.

Clinical Outcomes of Refractive Accommodative Esotropia in Korean Adolescent Patients

PURPOSE: To report the clinical course of refractive accommodative esotropia (AE) and to determine whether the strabismus resolves during the adolescent years in Korean patients. METHODS: A total of 32 adolescent patients with AE associated with hyperopia were retrospectively reviewed. Ocular alignments, amblyopia, stereopsis, changes in refractive error with time after glasses prescribed, and clinical characteristics were studied. RESULTS: The mean age and follow-up were 14.9 and 10.1 years, respectively at the final visit. The Initial and final refractive errors were 5.16 and 2.52 diopters (D), respectively. Spectacles were initiated at a mean age of 4.7 years, and intentional undercorrection initiated from a mean age of 6.3 years. Hyperopic reduction after prescribing glasses followed the formula: Diopter (D) = 5.23 - 0.02 (Time) - 0.03 (Time)**2. Initially, 16 out of 32 patients (50%) showed fully corrected hyperopia, and eventually, 71.9% wore partially corrected spectacles. The mean change of hyperopia per year was 0.26 D. Six out of 32 patients (18.8%) were successfully discontinued from hyperopic spectacles and the mean age of weaning was 14.7 years. Intentional initial undercorrection did not affect hyperopic reduction (p = 0.123). CONCLUSIONS: AE persists through adolescence for a majority of Korean patients. These patients need to be carefully monitored during follow-up periods because most do not outgrow their hyperopia and need to using spectacles.

Postoperative Refractive Changes after Optic Capturing

PURPOSE: To present postoperative refractive changes in patients with optic capturing. METHODS: This retrospective review was comprised of 81 eyes of 69 presenile and senile cataract patients who had undergone cataract surgeries, and 20 eyes of 11 pediatric cataract patients who had undergone irrigation and aspiration of the cataract, posterior continuous curvilinear capsulorhexis (PCCC) and optic capturing. Presenile and senile cataract patients were divided into three groups: Group I: Phacoemulsification with posterior chamber lens implantation (Phaco with PCL), 37 eyes; Group II: Phaco with PCL and PCCC, 22 eyes; Group III: Phaco with PCL, PCCC and optic capturing, 22 eyes. Preoperative target refractive error and postoperative refractive errors were compared postoperatively. RESULTS: Hyperopic shiftings were noticed in Groups I and II, but were not statistically significanct. However, statistically significant hyperopic shifting was found in Group III. In pediatric populations, we found no statistically significant refractive changes. CONCLUSIONS: PCCC alone does not cause refractive change postoperatively. When performing optic capturing, postoperative hyperopic shifting must be considered.

Thicknesses of Macular Retinal Layer and Peripapillary Retinal Nerve Fiber Layer in Patients with Hyperopic Anisometropic Amblyopia

This prospective study was performed to measure the macular and the peripapillary retinal nerve fiber layer (RNFL) thicknesses using optical coherence tomography (OCT) in patients with anisometropic amblyopia. Thirty-one patients with hyperopic anisometropic amblyopia were included. The macular retinal thickness and the peripapillary RNFL thickness were measured using OCT. The mean refractive error was +3.71 diopters (D) and +1.00 D, the mean macular retinal thickness was 252.5 micrometer and 249.7 micrometer, and the mean RNFL thickness was 115.2 micrometer and 109.6 micrometer, in the amblyopic eye and the normal eye, respectively. OCT assessment of RNFL thickness revealed a significantly thicker RNFL in hyperopic anisometropic amblyopia (P=0.019), but no statistically significant difference was found in macular retinal thickness (P> 0.05). In conclusion, the amblyopic process may involve the peripapillary RNFL, but not the macula. However, further evaluation is needed.

Phototherapeutic Keratectomy for Granular Corneal Dystrophy

PURPOSE: In this study, we evaluated the results of PTK(phototherapeutic keratectomy) for granular corneal dystrophy. METHODS: 5 eyes (4 patients) with granular corneal dystrophy were treated by PTK using Summit ExiMed UV200 and VSIX Star excimer laser systems. The epithelium was removed mechanically with a surgical blade. We used methylcellulose 1.0% as a surface modulator before laser ablation. Focal ablations of the central cornea with an ablation zone of 6.0 mm were performed. Mean ablation depth was 105 +/- 15.81 micrometer (range; 80~120 micrometer) Additional hyperopic PRK was performed on 4 eyes out of 5 eyes at the corneal mid-periphery up to maximum +5.00 D to prevent post-PTK hyperopic shift. Mean follow up period was 54.4 +/- 23.43months (range; 24~84months). RESULTS: Removal of corneal opacities allowed for improvement in both uncorrected visual acuity and best corrected visual acuity in all patients. There was an improvement in best-corrected visual acuity of a mean of 2.6 lines on the Snellen chart. Mean corneal thickness in the area of pathology decreased from 490.5 micrometer before surgery to 391.5 micrometer after surgery. There was a hyperopic shift in all the eyes in spite of additional hyperopic PRK by a mean of +2.44 +/- 0.99 D. There was mild recurrent dystrophic change in an eye but not significant enough to affect visual acuity during the follow up period. No major complications developed in any patients. CONCLUSIONS: Our results suggest that PTK is a safe and effective alternative to penetrating and lamellar keratoplasty in patients with granular corneal dystrophy. Mild post-PTK hyperopic shift occurred in all patients in spite of combined hyperopic PRK up to maximum +5.00 D correction at the corneal mid- peripheral zone according to the refractive powers.

Clinical Evaluation of AMO Phacoflex SI-30NB in the Aspect of A-constant

We inspected reliability of A-constant of AMO SI-30NB by comparing target diopter and actual postoperative refractive status. Group 1 comprised 191 eyes which were implanted AMO PhacoFlex SI-30NB with corneal incision. Group 2 comprised 45 eyes implanted Pharmacia 812C with scleral incisions. Group 3 comprised 17 eyes implanted AMO OgaciFlex SI-30NB with corneal incision. Refraction was performed on post operative day 1, day 5, day 14, 1 month, and 3 month. It revealed hyperopic shift of 0.31 to 0.40 diopter compared to the target diopters in both Group 1 and Group 3 and no statistical difference was found between two groups(p value>0.05). On the other hand, Group 2 were statistically significant(p value<0.01). We attempted mathematical modelling of this phenomenon and the cause of hyperopylene haptics, structural weakness of haptic-optic junction, and the structure of SI-30NB itself.

Compartive Accuracy of the SRK II, SRK/T and Holladay Formulas for Intraocular Lens Power Calculation in Severe Myopic Eyes

The predictive accuracy of the SRK II, SRK/T and Holladay formulas was evaluated in 22 eyes with sever myopia who had phacoemulsification and implantaton of posterior chamber IOL without suture. These patients were followed up for at least 6 months postoperatively. Correlation coefficient between the predicted refraction and actual refraction was 0.57(P0.05). The percentage of the eye with hyperopic shift(more hyperopic actual refraction than the predicted refraction) was 77% in the SRK II, 77% in the SRK/T and 86% in the Holladay, but there was no statistically significant difference between each formula(p>0.05). In conclusion, the SRK/T has the better predictive accuracy than the SRK II and Holladay in severe myopia and hyperopic shift tends to occur with the application of all three formulas.

The Effect of Holmium:YAG Laser Thermokeratoplasty on Corneal Astigmatism in Rabbits

This animal study was conducted to investigate the effect of holmium:YAG laser thermokeratoplasty on correction of hyperopic astigmatism. A pulsed holmium:YAG laser emitting a wavelength of 2.06 micrometer was used. Arcuate, reverse arcuate, linear patterns of laser burn were applied along the flat corneal meridian and their effects on the rabbit corneal curvature were studied. Keratometric measurements and cycloplegic refractive error were determined preoperatively, one, two, and three months after operation. The changes of refractive astigmatism in three patterns of laser burn were 0.8130, 3.0243, 0.8437 diopter, respectively, compared to that of the control group on postoperative three months. The changes of keratometric astigmatism were 1.1719, 3.0737, 0.7812 diopter, respectively, compared to that of the control group on postoperative three months. We found that holmium:YAG laser thermokeratoplasty is effective in steepening flat corneal meridian, and the most effective pattern is reverse arcuate type. In future holmium:YAG laser thermokeratoplasty might be clinically applicable as a operation of hyperopic astigmatism correction.