Effect of Intravitreal Aflibercept on Corneal Endothelial Cells.

AIM: To determine the effect of repeated intravitreal injections of aflibercept on the corneal endothelium in patients with diabetic macular edema (DME) and macular edema due to retinal vein occlusion (RVO). METHODS: In a prospective study conducted between January 2021 and November 2023, a total of 87 treatment-naive eyes with DME and RVO were evaluated. The exclusion criteria were surgery or laser intervention during the follow-up period, contact lens wear, cataract surgery in the last 6 months, dystrophy, or other corneal condition that may cause endothelial damage. In addition to routine examinations on the day of application, we also measured the corneal endothelium using specular microscopy on the 1st, 4th and 8th day of injection. We evaluated 4 parameters: endothelial cell density (CD), hexagonality (HEX), coefficient of variability (CV) and central corneal thickness (CCT). First of all, we evaluated the entire cohort of eyes, and then divided it according to 2 criteria; the diagnosis into DME/RVO and according to the lens status into phakic/pseudophakic eyes. RESULTS: A total of 87 eyes of 68 patients were evaluated. The average age of the patients at the time of diagnosis was 66.8 ±9.3 years. Within the cohort 51 (59%) eyes were phakic and 36 (41%) pseudophakic. A total of 61 (70%) eyes with a diagnosis of DME were treated, and 26 (30%) with RVO. During the follow-up, there were no significant changes in the average values of CD, HEX, CV, CCT due to aflibercept treatment, either in the whole group or in subgroups according to diagnosis or lens condition. CONCLUSIONS: The results of this study suggest that intravitreal administration of aflibercept in patients with DME and RVO did not have an impact on corneal endothelial parameters, including CCT, HEX, CD and CV. These parameters were measured using endothelial microscopy during an 8-injection observation period.

The effect of hyperbaric oxygen therapy on corneal endothelial structure and anterior segment parameters.

PURPOSE: To assess the effect of hyperbaric oxygen therapy (HBOT) on corneal endothelial structure and anterior segment parameters in healthy eyes. METHODS: 17 eyes of 17 patients who were scheduled to receive HBOT for other than ophthalmologic indications were investigated in this prospective study. Central corneal thickness (CCT) and corneal endothelial properties were evaluated using a specular microscope. Endothelial cell density (ECD), average cell area (AVG), coefficient of variation in cell size (CV), percentage of hexagonal cells (HEX), CCT, intraocular pressure (IOP), spherical equivalent (SE), axial length (AL) and anterior chamber depth (ACD) values were measured before the HBOT, after the 1st session, and after the 20th session of therapy. RESULTS: 47% of the patients (n = 8) received HBOT because of avascular necrosis, 35% (n = 6) due to sudden hearing loss, 12% (n = 2) for diabetic foot, and 6% (n = 1) for wound infection. The mean IOP was 14,80 mmHg before HBOT, 14,20 mmHg after the 1st session, and 13,73 mmHg after the 20th session. The mean ACD was 3,38 mm before HBOT, 3,34 mm after the 1st session, and 3,16 mm after the 20th session. Although the mean IOP and ACD decreased after HBOT sessions, it was not statistically significant (p > 0.05). A significant reduction was observed in SE values after 20 sessions of HBOT compared to the values measured before HBOT (p = 0,009). The mean ECD was 2572,53 ± 261,51 cells/mm2 before HBOT, 2554,47 ± 236,13 after the 1st session, and 2563,13 ± 226,92 after the 20th session. When the corneal properties measured before and after HBOT sessions were compared, no significant difference was found in terms of CCT, ECD, AVG, CV, and HEX (p > 0.05). CONCLUSION: We observed no significant change in CCT, corneal endothelial layer properties, and anterior segment morphology after the 1st session, and after the 20th session of HBOT. Although HBOT reduced IOP and ACD, it was not statistically significant. HBOT may lead to a significant decrease in SE values after the 20th session.

Is Pterygium Morphology Related to Loss of Corneal Endothelial Cells? A Cross-Sectional Study.

PURPOSE: To determine the difference in mean corneal endothelial cell density (CECD) between the healthy and diseased eyes of the patients with unilateral pterygium with different morphology patterns by using a non-contact specular microscope (SP2000: Topcon Corporation, Japan) and to find out any relationship between severity of pterygium and daily sunlight exposure with the CECD loss. METHODS: A descriptive cross-sectional prospective study was carried out at Al-Shifa Trust Eye Hospital (ASTEH), Rawalpindi, Pakistan from 21st January 2019 to 22nd January 2020. Two hundred eyes (n= 100 patients) of age range18 -68 years with unilateral pterygium were selected. Necessary demographic data and essential variables like age, smoking status, occupation, and daily direct sunlight exposure were determined. The severity of pterygium (grading) based on its morphology was determined by slit-lamp examination. CECD of each patient was carried out using a non-contact Specular Microscope. The healthy eye (without pterygium) of a patient was considered as control. RESULTS: The age range in this study was 18-68 years, with a mean age of 43.80 ± 24.37 years with a male to female ratio of 1.6:1 (62.00% males vs 38% females). Out of six occupations, the most common occupation was labour/construction work (n=31) followed by farming (n=27). The study reported a mean corneal endothelial cell density (CECD) of 2411.61±143.64 vs 2751.41 ± 123.674 cells/mm2 in diseased and normal eyes, respectively (p-value = 0.0001). CECD was lower in grade 3 pterygium compared to less severe pterygium { grade 3 (Fleshy) =2261 cells/mm2 vs grade 2 (Intermediate)= 2413 cells/mm2 vs grade 1 (Atrophic)=2459 cells/mm2} although this difference between the groups was not found to be significant (p=0.065). No significant association between sunlight exposure and CECD loss was observed (p=0.065). CONCLUSION: This study concluded that the mean corneal endothelial cell density in patients with unilateral pterygium using a non-contact specular microscope were 2411.61±143.64 cells/mm2.

Lack of association between obstructive sleep apnea syndrome and specular microscopic features of the corneal endothelium.

BACKGROUND: Obstructive sleep apnea syndrome (OSAS) is characterized by recurrent episodes of hypoxemia and hypercapnia during sleep. The aim of this study was to determine whether OSAS causes significant changes in corneal endothelium detectable by specular microscopy. METHODS: This prospective, cross-sectional study compared the specular microscopic features of the corneal endothelium of patients with OSAS and age-and gender-matched controls. Patients diagnosed with OSAS by polysomnography in the sleep unit were classified using apnea-hypopnea indexes into two groups as mild-moderate OSAS group and severe OSAS group. All participants were divided into three age groups: 30-45, 46-60, and > 60 years. Corneal endothelial cell density (ECD), percentage of hexagonal cells (Hex), and coefficient of variation of cell area (CV) were obtained using a non-contact specular microscope. The measurements of each group were compared statistically. RESULTS: A total of 66 patients (51.1 ± 9.4 years) and 88 controls (49.2 ± 10.5 years) were examined. The mild-moderate OSAS group and the severe OSAS group had no significant differences in measures of specular microscopy compared with the controls (ECD, p = 0.84; Hex, p = 0.18; CV, p = 0.41). The mean values of ECD, Hex, and CV were 2552.56 ± 302.49 cells/mm2, 54.13 ± 8.13%, and 36.41 ± 5.92, respectively, in the mild-moderate OSAS group; 2510.52 ± 377.12 cells/mm2, 54.85 ± 8.68%, and 34.77 ± 5.02, respectively, in the severe OSAS group; 2543.37 ± 286.94 cells/mm2, 51.89 ± 9.09%, and 36.03 ± 5.32, respectively, in the control group. CONCLUSIONS: There were no significant differences in corneal endothelial features between patients and controls. Although OSAS causes systemic hypoxia, its effects do not appear to result in corneal endothelial alterations detectable by specular microscopy.

A study of endothelial cell count pre- and post-neodymium-doped yttrium aluminum garnet laser iridotomy in subacute angle closure using specular microscope.

AIM: The aim of this study was to study the effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser iridotomy on corneal endothelial cell count in patients with subacute angle closure using specular microscope. MATERIALS AND METHODS: In this prospective study, 50 cases of narrow-angle Grade 1 and Grade 2 (Shaffer gonioscopic grading) visiting the Regional Institute of Ophthalmology, Government Medical College, Amritsar underwent Nd:YAG laser peripheral iridotomy. After obtaining informed written consent, specular microscopy was performed before and after iridotomy at 1 week, 1 month, 3rd month, and at 6th-month follow-up visits. Central, nasal, and temporal endothelial cell counts were evaluated through noncontact specular microscopy. RESULTS: The mean participant age was 51.52 ± 7.9 years, and majority of the participants were females (76%). The mean IOP before the laser was 19.25 ± 1.914 mmHg and it varied from 18.50 ± 1.647 to 18.25 ± 1.699 mmHg (day 1, p = 0.06 and at 6 months, p = 0.04) following laser procedure. The mean corneal endothelial cell count at superotemporal site before laser peripheral iridotomy was 2844 ± 260, and this value decreased to 2807 ± 263, 2699 ± 267, 2656 ± 270, and 2591 ± 275 cells/mm2 at postiridotomy, 1, 3, and 6 months' follow-up visits, respectively; these differences were statistically significant (p < 0.05). The mean total energy required to produce iridotomy was 14.88 ± 6.71 mJ, ranging from 5 to 37 mJ. The linear regression analysis indicated no statistical correlation between change in endothelial cell count at the treated site and total mean energy used. No significant difference was found between preiridotomy and postiridotomy corneal thickness at any site. CONCLUSION: This study demonstrated a significant endothelial cell loss at the treated site in 6 months' follow-up and suggested that Nd:YAG laser iridotomy may pose hazard to the corneal endothelium, although corneal decompensation at the treated site or as a whole was not seen.

Comparison of central corneal thickness and endothelial cell measurements by Scheimpflug camera system and two noncontact specular microscopes.

PURPOSE: To investigate the correlation of Scheimpflug camera system and two noncontact specular microscopes in terms of central corneal thickness (CCT) and corneal endothelial cell morphology measurements. METHODS: One hundred eyes of 50 healthy subjects were examined by Pentacam Scheimpflug Analyzer, CEM-530 (Nidek Co, Ltd, Gamagori, Japan) and CellChek XL (Konan Medical, California, USA) via fully automated image analysis with no corrections made. Measurement differences and agreement between instruments were determined by intraclass correlation analysis. RESULTS: The mean age of the subjects was 36.74 ± 8.59 (range 22-57). CCTs were well correlated among all devices, with having CEM-530 the thinnest and CellChek XL the thickest measurements (intraclass correlation coefficient (ICC) = 0.83; p < 0.001 and ICC = 0.78; p < 0.001, respectively). Mean endothelial cell density (ECD) given by CEM-530 was lower than CellChek XL (2613.17 ± 228.62 and 2862.72 ± 170.42 cells/mm2, respectively; ICC = 0.43; p < 0.001). Mean value for coefficient of variation (CV) was 28.57 ± 3.61 in CEM-530 and 30.30 ± 3.53 in CellChek XL. Cell hexagonality (HEX) with CEM-530 was higher than with CellChek XL (68.70 ± 4.16% and 45.19 ± 6.58%, respectively). CONCLUSIONS: ECDs with CellChek XL and CEM-530 have good correlation, but the values obtained by CellChek XL are higher than CEM-530. Measurements for HEX and CV differ significantly and show weak correlation. Thus, we do not recommend interchangeable use of CellChek XL and CEM-530. In terms of CCTs, Pentacam, CEM-530 and CellChek XL specular microscopy instruments are reliable devices.

Accuracy of Cirrus HD-OCT and Topcon SP-3000P for measuring central corneal thickness.

PURPOSE: To compare and analyze the interchangeability of three measuring systems, each based on a different technique, for central corneal thickness (CCT) analysis. METHODS: CCT measurements were measured using optical coherence tomography (OCT), non-contact specular microscopy (NCSM), and ultrasonic pachymetry (USP) in 60 eyes of 60 healthy patients with a mean age of 66.5±15.0 years and a mean spherical equivalent of 0.43±1.14 D. Analysis of variations in measurement concordance and correlation among the three different methods were performed. Comparison of CCT measurements were done using Bland-Altman plots (with bias and 95% confidence intervals), intraclass correlation coefficient (ICC), and paired t-student analysis. RESULTS: Mean CCT values were: 549.20±26.91µm for USP (range 503-618µm), 514.20±27.49µm for NCSM (range 456-586µm) and 542.80±25.56µm for OCT (range 486-605µm). CCT values obtained with NCMS were significantly lower than those obtained with OCT and USP methods. NCMS CCT value was 36.08±10.72µm lower than USP value (p<0.05), and NCMS CCT value was 7.88±8.86µm lower than OCT value (p<0.05). ICC between USP-NCSM pair was 0.488 and 0.909 between USP-OCT pair. CONCLUSION: OCT and UPS offered highly comparable results, whereas NCSM offered lower mean CCT values compared to the other two methods. Therefore, NCSM should not be considered a reliable method for measuring CCT and should rather be considered for assessing longitudinal changes in the same patient.

Age-related changes of corneal endothelial cell in healthy Chinese tree shrew measured by non-contact specular microscope.

AIM: To determine the impact of age on the morphology of endothelial cells and central corneal thickness (CCT) in Chinese tree shrew. METHODS: One-hundred and twenty eyes of 60 healthy Chinese tree shrews were studied. Based on age, the tree shrews were divided into four groups. After general anesthesia, the images of endothelium were acquired using non-contact specular microscope Topcon 3000P. Eight parameters of corneal endothelial cells were measured by built-in software, including CCT, endothelial cell density (ECD), percent hexagonality (HG%), coefficient of variability (CV), size of minimal cell (Smin), size of maximal cell (Smax), average cells size (Savg) and size standard deviation (Ssd). Data were analyzed using STATA software. The differences of eight parameters among groups and correlations with age were analyzed. RESULTS: In all studied animals, the average CCT was 249.6±20.29 µm (202-301 µm), ECD was 3080.72± 460.76 cells/mm2 (1239.6-4047.6 cells/mm2) and CV was 29.10±7.60 (13.6-54.6). CV was significantly different among different groups (P<0.001). Strong correlation with age was found in ECD, Smax, Savg, Ssd and CV. CONCLUSION: Cornea of Chinese tree shrews had half CCT of human cornea and similar ECD, CV and size of corneal endothelial cells. Young adult tree shrews had higher ECD, HG% and low CV. ECD, Smax, Savg, Ssd and CV correlated with age significantly.

Corneal endothelial cell density and morphology in rabbits' eyes using contact specular microscopy / Densidade celular e morfologia das células do endotélio da córnea de coelhos obtidas com microscopia especular

ABSTRACT: The goal of this study was to describe the normal values of corneal endothelial cell density and hexagonality in healthy rabbits' eyes using contact specular microscopy. Both eyes of 18 rabbits, males and females, of different ages were evaluated. The eyes were divided into three groups of 12 each according to the age range of the animals: G1 (6 months old), G2 (12 months old), and G3 (48 months old). Parameters studied included mean endothelial cell density and hexagonality. For Group I, the mean cell density was 2307 cells per mm2. For GII, the mean cell density was 1895 cells per mm2. For G III, the mean cell density was 1818 cells per mm2. Cell density decreased significantly with aging (P<0.001) among the three groups. Pleomorphism in the rabbits of GI was 74.33±10.08. In the rabbits of GII it was 71.83±11.38. In the rabbits of GIII it was 64.02±28.80. Significant differences (P<0.001) were evident between GI and GIII and GII and GIII but not between Groups I and II. The results showed a decrease in number of cells and hexagonality with aging. Corneal endothelium of rabbits suffers changes due to advancing age both in terms of cell density and morphology.

RESUMO: Objetivou-se avaliar a densidade celular e a hexagonalidade do endotélio da córnea de coelhos saudáveis usando um microscópio especular de contato. Os dois olhos de 18 coelhos, machos ou fêmeas, de diferentes idades foram avaliados. Os olhos foram separados em três grupos de 12 olhos cada em função da idade: G1 (6 meses de idade), G2 (12 meses de idade) e G3 (48 meses de idade). Os parâmetros estudados incluíram a densidade celular e a hexagonalidade. Para o Grupo I, a densidade celular média foi de 2307 células por mm2. Para GII, a densidade celular média foi de 1895 células por mm2. Para G III, a densidade celular média foi de 1818 células por mm2. A densidade celular diminuiu significativamente com o envelhecimento (P<0,001) entre os três grupos. O pleomorfismo nos coelhos de GI foi de 74,33±10,08. Nos coelhos do GII foi 71,83±11,38. Nos coelhos de GIII foi de 64,02±28,80. Diferenças significativas (P<0,001) foram evidentes entre GI e GIII e GII e GIII, mas não entre os Grupos I e II. Os resultados revelaram diminuição da densidade celular e da hexagonalidade com o avanço da idade. O endotélio da córnea de coelhos sofre alterações devido ao avanço da idade tanto na densidade celular e quanto na morfologia.

Influence of applied corneal endothelium image segmentation techniques on the clinical parameters.

The corneal endothelium state is verified on the basis of an in vivo specular microscope image from which the shape and density of cells are exploited for data description. Due to the relatively low image quality resulting from a high magnification of the living, non-stained tissue, both manual and automatic analysis of the data is a challenging task. Although, many automatic or semi-automatic solutions have already been introduced, all of them are prone to inaccuracy. This work presents a comparison of four methods (fully-automated or semi-automated) for endothelial cell segmentation, all of which represent a different approach to cell segmentation; fast robust stochastic watershed (FRSW), KH method, active contours solution (SNAKE), and TOPCON ImageNET. Moreover, an improvement framework is introduced which aims to unify precise cell border location in images pre-processed with differing techniques. Finally, the influence of the selected methods on clinical parameters is examined, both with and without the improvement framework application. The experiments revealed that although the image segmentation approaches differ, the measures calculated for clinical parameters are in high accordance when CV (coefficient of variation), and CVSL (coefficient of variation of cell sides length) are considered. Higher variation was noticed for the H (hexagonality) metric. Utilisation of the improvement framework assured better repeatability of precise endothelial cell border location between the methods while diminishing the dispersion of clinical parameter values calculated for such images. Finally, it was proven statistically that the image processing method applied for endothelial cell analysis does not influence the ability to differentiate between the images using medical parameters.

Comparison of different methods for the measurement of central and paracentral corneal thickness in post-LASIK eyes / 中华实验眼科杂志

Background Accurate measurement of corneal thickness is very important during the pre-and post-operative management of corneal surgical procedures,especially laser-assisted in-situ keratomileusis (LASIK),which is the most popular approach to the correction of refractive errors currently.This may be particularly important for the patients who have undergone previous laser refractive surgery with suboptimal outcomes and are being considered for an enhancement procedure.Objective This study was to compare the measuring outcomes of corneal thickness by slit-scanning pachymetry,non-contact specular microscope,anterior segment optical coherence tomography (AS-OCT)and ultrasound pachymetry,with a focus on central and midperipheral (from the central 3.0 mm) region of cornea in post-LASIK eyes.Methods Sixty-four right eyes of 64 patients who received LASIK were collected in Henan Eye Institute,Henan Eye Hospital from March to June 2011 with the equivalent spherical diopter of (-4.75±2.38)D and horizontal corneal diameter of (11.36±0.32)mm.Central corneal thickness was measured on each eye by using non-contact specular microscope (Topcon SP-3000P),slit-scanning pachymetry (Orbscan Ⅱ),AS-OCT and A-type ultrasound pachymetry,respectively,and the paracentral corneal thickness including 12:00,2:00,6:00 and 10:00 meridian was measured using Orbscan Ⅱ,non-contact specular microscope and AS-OCT.The measuring values and the agreement from different instruments were compared and evaluated.Results The mean central corneal thickness was (467.12±31.10)tμm for AS-OCT,(466.67±30.99)μm for ultrasound pachymetry,(441.84 ± 33.65) μm for specular microscopy and (422.51 ± 44.09) μm for Orbsan Ⅱ,respectively,showing a significant difference among the four methods (F =23.730,P =0.000).The central thickness value of the A-type ultrasound pachymetry was significantly higher than that of Orbsan Ⅱ or non-contact specular microscope (q =6.940,6.720,both at P =0.000).Compared with Orbscan Ⅱ,the measuring values of non-contact specular microscope and AS-OCT were significantly higher (q =-5.54,6.940,both at P =0.000),and the measuring value of AS-OCT was significantly higher that of non-contact specular microscope (q =6.800,P =0.000).The lowest difference value (25.3 μm)and the best agreement was found between the ultrasound pachymetry and AS-OCT.The paracentral corneal thickness values in 12:00,2:00,10:00,6:00 meridians were highest for Orbsan Ⅱ and the next for AS-OCT,and non-contact specular microscope had the lowest values,with significantly differences among them (F =5.020,22.950,67.890,18.850,all at P ＜ 0.01).Conclusions The corneal thickness values vary with the different instruments.Orbsan Ⅱ underestimates the central corneal thickness and overestimates the midperipheral corneal thickness,and non-contact specular microscope underestimates both the central and midperipheral corneal thickness.The measuring outcome from AS-OCT has a good agreement with ultrasound pachymetry and therefore they can be used interchangeably.

Comparison among different noncontact specular microscopes for the detection of corneal endothelial cell density / 中华实验眼科杂志

Background Clinical research showed that the corneal endothelial cell density value from different corneal specula microscopies exist diversity.The relevant literature of SP02,Tomey EM-3000 and SP3000P is still seldom up to now. Objective This research was to assess the repeatability of endothelial cell density measurements by SP02,Tomey EM-3000 and SP3000P respectively and the agreement among 3 kinds of endothelial microscopes.MethodsFifty-four healthy volunteers with the age 17-38 years old were included this research.The written informed consent was obtained from each subject before examination.The corneal endothelial cell densities in the right eyes were analyzed with SP02,Tomey EM-3000 and SP3000P respectively for 3 times under the automatic mode,and the analytical procedure of SP3000P measurement were divided into automatic mode SP3000P (A) and manual correction modes SP3000P( M).The repeatability of each specula microscopy was analyzed by calculating the intraclass correlation coefficients (ICC) and coefficient of variation ( CV ),and the 95％ confidence intervals and plotting Bland-Altman graphs were used to analyze the agreement among these methods.ResultsThe mean corneal endothelial cell densities in the population ＜24 years were significantly higher than the ones ≥ 24 years (t =3.692,P＜0.05 ),but no statistical difference was found between different gender ( t =0.335,P =0.739 ).The mean corneal endothelial cell densities were ( 3058 ± 260 ),( 2954 ± 229 ),( 2668 ± 258 ),( 2734 ± 268 ) cell/mm2 ; the ICCs were 0.957,0.940,0.972 and 0.972 and the CV were 0.063,0.061,0.056,0.058 for SP02,Tomey EM-3000,SP3000P (A) and SP3000P ( M ) respectively.The 95％ confidence intervals were ( - 100.8 - 306.8 ),( 162.6 - 617.4 ),( 109.9-494.1 ) and ( -0.6 - 132.6 ) cell/mm2 for between SP02 and Tomey EM-3000,SP3000P ( A ) and SP02,SP3000P(A) and Tomey EM-3000,SP3000P(A) and SP 3000P(M) respectively.ConclusionsSP02,Tomey EM-3000 and SP3000P(A) have good repeatability in the measurement of corneal endothelial cell density,however the outcome is different.Therefore,it is not interchangeable for the detection of corneal endothelial cell density.The differences of corneal endothelial cell density obtained from these instruments shall be paid high attention for their differences.SP3000P(A) and SP3000P(M) can be used interehangeably and SP3000P(A) is a preferable choice due to its convenience and quickness.

Comparison of Corneal Thickness Measurements with Noncontact Specular Microscope and Ultrasonic Pachymeter

PURPOSE: To evaluate the corneal thickness values before and after refractive keratoplasty with the Topcon SP-2000 noncontact specular microscope(Topcon American Corp.) and the common standard ultrasonic pachymeter. METHODS: Corneal thickness was measured in 40 eyes of 20 patients, 5 times each before and after keratoplasty, with the Topcon SP-2000P and an ultrasonic pachymeter (DGH 1000, DGH Technology Inc.). The main outcome measures were accuracy and reproducibility as assessed with coefficient of variation (CV) of corneal thickness measurements. RESULTS: The reproducibility of corneal thickness measurements was better with the ultrasonic pachymeter (CV 0.36%) than with the Topcon SP-2000 (CV 1.23%). Mean corneal thickness measured by the Topcon SP-2000P before and after keratoplasty was significantly less than the mean values obtained with the ultrasonic pachymeter (14.4 micro meter; P<.0001, 5.6 micro meter; P<.01; respectively). Compared with theoretical ablated corneal thickness, ablated corneal thickness measured with the Topcon SP-2000P was significantly less (P<.01) than values obtained with the ultrasonic pachymeter (P=0.07) CONCLUSIONS: The noncontact Topcon specular microscope provides measurements of corneal thickness that are significantly less than those of the ultrasonic pachymeter, both before and after keratoplasty. These results indicate that these 2 techniques are not clinically comparable, thereby precluding interchangeable use of their data in planning or assessing keratoplasty.

The Evaluation of the Endothelial Cells after Cataract Extraction and IOL Insertion in Patients with Corneal Guttata

When the corneal endothelium is injured by intraocular surgery, corneal edema occurs above the threshold level. Preoperative examination of corneal endothelium is valuable in prediction the degree of transparency of the cornea. We conducted this study to elucidate what factors affect corneal endothelial cells in performing the cataract extraction and IOL insertion and what is necessary to minimize the corneal endothelial damage. We performed pacoemulsification and IOL insertion in guttata patients, and preoperative and postoperative endothelial examination was done by using specuar microscope and pachymeter. Although the mean of endothelial cell density was diminished from 1498.7cells/mm2 to 1301cells/mm2 after operation. visible edema was not detected by slit lamp examination and visual acuity was improved from 0.15 to 0.48. The older the patient`s age, the longer the time of phaceemulsification; as the ages of the patients are increased, postoperative corneal thicknesses were increased and postoperative endothelial cell densities were decreased. The endothelial cells were relatively well preserved after cataract operation in patients of preoperative diminished endothelial cells. We suggest that when performing the cataract operation in patients of decreased endothelial function, one must use appropriate large amount of viscoelastic substances, and minimize phacoemulsification power and time in as short operation time as possible by accurate surgical technique. We also believe that periodic postoperative endothelial examination is necessary in patients with decreased endothelial function.

The Corneal Endothelial Cell Density in Korean by the Different Types of Specular Microscopy

The normal corneal endothelial cell count was measured by the non-contact(Nikon, AS-1, Japan) and contact type(Bio-optic, LSM 2000, USA) specular microscopy. The results of two types were compared to investigate the possible differences in types of specular microscopy. No statistically significant differences were found between the results from the non-contact type and those from the contact type; the mean number of normal Korean corneal endothelial cells according to the age was 2795 in the 2nd decade, 2615 in the 3rd decade, 2463 in the 4th decade, 2283 in the 5th decade, 2119 in the 6th decade, 2019 in the 7th decade and 1920 over the 8th decade.