A cross-sectional study to determine the normal corneal epithelial thickness in Indian population using 9-mm wide optical coherence tomography scans

Purpose:To study the corneal epithelial thickness with 9-mm scans of optical coherence tomography in normal Indians with appropriate representation of all age groups.Methods:This was a cross-sectional observational study. 263 patients were divided into the age groups 5–20 years, 21–35 years, 36–50 years and more than 51 years were recruited for the study. All patients underwent a detailed ophthalmic examination. Patients found to have any ocular surface or intraocular disease condition (except cataract and refractive error), or who had undergone any ophthalmic surgery in the past, or had corneal topography changes suggestive of corneal ectasias (screened in patients with astigmatism more than 3 diopters) or had been continuously using any topical medication in either eye for a period of 3 months or more with the last instillation being within 1 month of inclusion in the study were excluded. All subjects underwent corneal epithelial thickness measurement with anterior segment optical coherence tomography (AS-OCT) on the Avanti OCT (Model RTVueXR1002, Optovue, USA). The corneal epithelial thickness (CET) data from 25 sectors in each eye were analyzed.Results:263 right and left eyes of 263 patients were analyzed in the study. Mean CETs in the central 2 mm zone were 54.13 ± 4.51 μm and 54.37 ± 3.75 μm for the right and left eyes, respectively. The superior peripheral sectors and inferior paracentral sectors were the thinnest and the thickest sectors, respectively, in both eyes.Conclusion:CET parameters for Indian eyes are comparable to those reported from racially distinct and geographically distant study subjects.     

Corneal and corneal epithelial thickness distribution characteristics in healthy North Indian eyes using spectral domain optical coherence tomography

Purpose:To determine the pattern of corneal thickness and epithelial thickness distribution in healthy North Indian eyes by using spectral domain optical coherence tomography (SD-OCT).Methods:The observational study measured total corneal and epithelial thickness in the central 2 mm zone and eight sectors each in paracentral 2–5 mm (ring 1) and midperipheral 5–7 mm (ring 2) zones on SD-OCT.Results:The study included 67 eyes of 67 subjects with a male:female ratio of 32:35 and mean age of 25.04 ± 4.54 years. The mean central corneal and epithelial thicknesses were 505.97 ± 30.12 mm and 60.48 ± 8.37 mm, respectively. The epithelium of inferior and infero-nasal sectors in ring 1 and inferior sector in ring 2 was significantly thicker than the radially opposite sectors of the respective rings (P = 0.001; P = 0.01 and P = 0.02, respectively). Sector-wise analysis did not reveal any significant correlation between the total corneal thickness and epithelial thickness (all P > 0.05) except in the outer superior sector where there was a weak positive correlation (r = 0.28, P = 0.02). Central epithelial thickness in males (60.59 ± 9.28 mm) and females (60.37 ± 7.58 mm) was comparable (P = 0.91). Pachymetry was thinnest in the inferior, inferonasal, and inferotemporal sectors in 44.79% of eyes (n = 30), while thinnest epithelium was seen in the superior, superonasal, and superotemporal quadrants in 50.75% of eyes (n = 34)Conclusion:The epithelial thickness distribution in this sample of topographically normal healthy North Indian eyes was nonuniform and independent of the underlying corneal thickness. Epithelium was thinner in the superior cornea, whereas total corneal thickness was minimum in the inferior part.     

Evaluation of changes in corneal endothelium in chronic kidney disease

Purpose:Chronic kidney disease (CKD) is an emerging health problem worldwide. In CKD corneal endothelial changes also occur probably due to accumulation of inflammatory cytokines and increased multiple toxic products. The aim of this study was to analyze the effect of CKD on corneal endothelium and correlate the findings with severity of disease with help of noninvasive technique.Methods:The study comprised 75 eyes of 75 cases divided into three groups with group A comprising of CKD cases on dialysis, group B of nondialysis CKD cases, and group C of controls. Each group had 25 cases each of either sex and between 15–80 age groups. All patients were investigated for blood urea, serum creatinine, and blood sugar and underwent complete ophthalmic examination of both eyes along with wide-field specular microscopy examination.Results:The majority of patients (33.3%) belonged to age range of 61–70 years with male predominance and the most common cause of CKD was found to be diabetes with 17 (34%) cases. We found normal corneal endothelial cell density (ECD) with the mean ECD of 2364.52 ± 397.72 mm² in the dialysis group, 2467.8 ± 352.88 mm² in nondialysis group, and 2521.68 ± 250.26 mm² in the control group of patients. However, we found significant increase in coefficient of variation (CV) with 36 ± 5.8% in dialysis group, 37 ± 4.5% in nondialysis group and 32 ± 0.8% in controls (P = 0.001) and decreased hexagonality (Hx) with 47 ± 7.3% in dialysis group, 46 ± 4.7% in nondialysis group and 51 ± 6.7% in the controls (P = 0.031). This showed increased tendency of pleomorphism and polymegathism in corneal endothelial cells in CKD cases. No correlation was found between blood urea or serum creatinine levels with endothelial parameters in any group.Conclusion:CKD causes morphological changes like polymegathism and pleomorphism in corneal endothelium and hence these cases are more vulnerable and special care should be taken before any intraocular surgical procedure.     

Choroidal and retinal thickness variations in ocular albinism

Purpose:To study the retinal and choroidal thickness variations on enhanced depth imaging optical coherence tomography scans in ocular albinism (OA) and compare with age-matched healthy subjects.Methods: This retrospective observational study had 48 eyes of 24 patients diagnosed clinically as OA and age, sex, and axial length-matched control healthy subjects. All patients underwent detailed ophthalmic examination and a single-line horizontal-raster enhanced depth imaging – optical coherence tomography scan (Spectralis, Heidelberg Engineering). Retinal and choroidal thickness was measured, compared, and analyzed between the two groups. Mann–Whitney U test was used for analysis between the two groups. P < 0.05 was considered significant.Results: The mean age was 28.3 ± 11.6 and 29.9 ± 10.6 years in the OA group and control group, respectively. Spherical equivalents ranged from −8.5D to +10.5D in the OA group and from −8.0D to +10.0D in the control group. The mean axial length between the two groups (P = 0.652) were comparable. The average retinal thickness (272 ± 34.3 vs. 213 ± 13.8 mm; P < 0.001) was greater in the OA group as compared to controls. The mean choroidal thickness (184 ± 78.4 vs. 287 ± 46.4 mm; P < 0.001) was significantly thinner in the OA group.Conclusion: Acquisition of OCT scans in OA can be challenging. This study showed that the subfoveal retinal thickness and choroidal thickness measured across the scans were significantly different in the OA group compared to controls. In the future, more studies are required to evaluate the role of the choroid and its relationship to emmetropization in albinism.     

The relationship between corneal subbasal nerve density and corneal sensitivity in patients with Fuchs endothelial corneal dystrophy

Purpose:The aim of this study was to investigate the association between alterations in corneal subbasal nerve plexus and tactile corneal sensitivity in patients with Fuchs’ endothelial corneal dystrophy (FECD).Methods:This retrospective, cross-sectional study included 24 (10 M/14 F) patients with FECD and 25 age- and sex-matched (10 M/15 F) healthy subjects as controls. Subjects with FECD were classified as having early (grades 1 and 2) and late (grades 3 and 4) disease. All subjects underwent central corneal tactile sensitivity measurements with the Cochet–Bonnet esthesiometer (Luneau Ophthalmologie, Chartres, France) and subbasal nerve density evaluation using in vivo confocal microscopy (IVCM). Association between corneal nerve plexus density and corneal sensitivity alterations were evaluated using the Mann–Whitney U test and the Spearman correlation test.Results:Compared to healthy subjects (mean age = 60.4 ± 7.5 years), patients with FECD (mean age = 60.6 ± 8.0 years) had worse central corneal sensitivity scores (5.9 ± 0.1 cm vs. 4.2 ± 0.8 cm; P < 0.001), reduced corneal nerve fibers (3.4 ± 1.3 nerves/frame vs. 5.0 ± 0.9 nerves/frame; P < 0.001) and lower corneal subbasal nerve plexus densities (2229.4 ± 364.3 μm/mm² vs. 1901.6 ± 486.8 μm/mm²; P = 0.050). Patients with late stage FECD demonstrated lower subbasal nerve densities as compared to those with early disease (2204.3 ± 313.1 μm/mm² (range = 1523–2552 μm/mm²); 1397.1 ± 227.4 μm/mm² (range = 1120-1834 μm/mm²); P < 0.001). In the FECD group, subbasal nerve density was found to be directly correlated with corneal sensitivity scores (r = 0.457, P = 0.025).Conclusion:Progressive loss of the corneal subbasal nerve plexus appears to be a consistent feature of FECD. Reduction of the corneal nerve plexus parallels the decrease in corneal sensitivity in this patient population.     

To compare central corneal thickness measurements obtained by Pentacam with those obtained by IOLMaster 700, Cirrus anterior segment optical coherence tomography and Tomey specular microscopy in normal healthy eyes

Purpose:To compare central corneal thickness measurements obtained by Pentacam with those obtained by IOL Master 700, Cirrus Anterior segment optical coherence tomography and Tomey Specular microscopy in normal healthy eyes.Methods:Two hundred and six eyes of healthy subjects were included in the study. Each subject was assessed by four different methods of measuring central corneal thickness using Pentacam, IOL Master 700, Cirrus AS-OCT and Tomey Specular microscopy by a single examiner.Results:The mean CCT [± standard deviation (SD)] for Pentacam, IOL Master 700, Cirrus AS-OCT and Tomey Specular microscopy were Pentacam (Oculus), AS-OCT (Cirrus), IOL Master 700 and Specular microscopy (Tomey) were 523.75 (±27.75), 525.29 (±28.81),517.13 (±28.43) and 512.82 (±27.60) μm, respectively. All the means were significantly different from one another (P < 0.000). The differences between pairs of mean central corneal thickness (CCT) for Pentacam and IOL Master, Pentacam and anterior segment- optical coherence tomography (AS-OCT), and Pentacam and Specular microscopy are statistically significant. Bland–Altman plots showed that pentacam and IOL Master 700 have the closest agreement, followed by AS-OCT. Specular microscopy was found to have the poorest agreement with Pentacam.Conclusion:We found that CCT measurements of Pentacam did not correlate with measurements of IOL Master, or AS-OCT or Specular microscopy. In clinical practice, the devices analyzed should not be used interchangeably due to low agreement regarding CCT values.     

Validating the use of U-tool as a novel method for measuring the corneal diameter in infants screened for congenital glaucoma

Purpose:The Castroviejo caliper is routinely used for measuring the corneal diameter in patients with primary congenital glaucoma, but needs an examination under anesthesia (EUA) or sedation. A simple U-shaped tool was devised to aid in the estimation of the corneal diameters of patients in settings where an ophthalmic caliper is not available or EUA is not feasible.Methods:Infants presenting to the congenital glaucoma clinic posted for EUA were recruited. The demographic details of the patients such as age, sex, and diagnosis were noted. A simple U-shaped tool was devised using three Schirmer strips or a printable ruler. Before the patient underwent a EUA, the corneal diameters were measured using the U-tool. During EUA, corneal diameters were measured using the Castroviejo caliper.Results:The mean age of infants was 6.7 ± 3.39 months (R = 1–12). The mean corneal diameter measured using the U-tool was 13.29 ± 1.33 mm and with Castroviejo caliper was 13.18 ± 1.39 mm. The difference between the corneal diameters measured using the two techniques was −0.114 mm with the Bland–Altman plot 95% Limits of agreement (LoA) from −0.965 to 0.737 mm. Corneal diameters measured with both instruments had a good correlation (Pearson’s correlation coefficient = 0.95, P < 0.001).Conclusion:U-tool can be used for screening congenital glaucoma by first-contact physicians or optometrists. It can also be used by ophthalmologists when EUA is delayed.     

Choroidal thickness in diabetic patients of Indian ethnicity

Purpose:To evaluate choroidal thickness (CT) change in various grades of diabetic retinopathy (DR) in comparison to age-matched healthy subjects.Methods:This prospective observational study included 227 eyes of 125 subjects with diabetes (study group: 58 females) and 197 eyes of 110 age-matched healthy subjects (control group: 66 females). Collected data included age, gender, duration of diabetes, glycemic control, comprehensive ocular examination, fundus photography, and CT measurement on spectral domain ocular coherence tomography using enhanced depth imaging.Results:Mean age in the study group was 57.0 ± 9.37 years (43–73 years). The mean age was 41.48 ± 5.43 years in the control group. Subjects with diabetes with (252.8 ± 55.6 microns) and without (261.71 ± 51.8 microns) retinopathy had significantly thinner choroids when compared to the control group (281.7 ± 47.7 microns; P = 0.032). Seventy-four of 227 eyes did not have any evidence of DR, 89 eyes had features of nonproliferative diabetic retinopathy (NPDR), and 33 eyes had treatment naïve proliferative diabetic retinopathy (PDR). Thirty-one PDR eyes had received previous laser photocoagulation. Subjects with diabetes without retinopathy had a greater subfoveal choroidal thickness (SFCT) than subjects with diabetes with retinopathy (P < 0.001). Eyes with PDR (243.9 ± 56.2 microns) had thinner SFCT than those with NPDR (238.98 ± 111.23 microns). There was no difference in the SFCT between treated (laser photocoagulation done; 251.784 ± 103.72 microns) and treatment naïve PDR (258.405 ± 89.47 microns, P = 0.23).Conclusions:Control eyes had greater SFCT compared to subjects with diabetes, with and without retinopathy. The thinning progressed with increasing severity of DR. Choroidal thinning may contribute to DR pathogenesis.     

Pupillodynamics and corneal spherical aberrations in a set of Indian cataract patients and its implications for aberrometric customisation of intraocular lenses

Purpose:Assessment of pupil diameter in various light conditions and the corresponding corneal spherical aberrations in a cohort of Indian eyes with bilateral senile cataracts and the possible use of this data in aberrometric customization of intraocular lenses (IOLs).Methods:In this prospective observational study done at a tertiary eye care centre in India, the selected patients were subjected to measurement of their pupil diameters in scotopic, mesopic, and photopic conditions as well as the corresponding corneal spherical aberrations, using the Sirius Topographer (Costruzione Strumenti Oftalmici, Florence, Italy). Shapiro–Wilk test, Independent t-test, ANOVA with Bonferroni correction on post-hoc testing were used for statistical analysis.Results:104 eyes of 52 patients were enrolled for the study. The mean age was 53 ± 11.88 years. The mean scotopic, mesopic, and photopic pupil sizes were 4.37 mm (4.11–4.63 mm), 3.92 mm (3.71 mm–4.15 mm), and 3.37 mm (3.18–3.67 mm), respectively. There was a statistically significant difference (P = <0.001) in the mean corneal spherical aberration measured at the 6 mm zone (0.23 ± 0.02 microns) and at the 4 mm zone (0.06 ± 0.01 microns).Conclusion:The mean corneal spherical aberration corresponding to the average mesopic pupil size of our patient population was substantially lower than that of the scotopic pupil size and also less than the amount corrected by most of the negative aspheric IOLs. This perhaps indicates the need for customising IOLs based on the spherical aberrations of cornea at the zone corresponding to the mesopic pupil diameter for optimal residual total postoperative spherical aberrations.     

Comparison of posterior corneal elevation in children with and without vernal keratoconjunctivitis using a new tomographer

Purpose:To assess the posterior corneal elevation (PCE) in children with vernal keratoconjunctivitis (VKC) and compare the same with that of age and gender-matched normal children.Methods:This was a case control study. We included 110 children attending the Pediatric ophthalmology outpatient department of a tertiary eye care center in South India between September 2019 and June 2020. Fifty-five children with VKC and 55 normal age and gender-matched children were examined by Sirius tomographer/topographer (CSO, Italy) to determine the PCE, thinnest corneal thickness (TCT), simulated K (Sim K), keratoconus front (KVf) and keratoconus vertex back (KVb). The parameters were compared between the two groups.Results:A total of 220 eyes of 110 children were examined. The mean age in both groups was 10.44 ± 3.28 years, each group included 44 males and 11 females. There was no statistically significant difference in TCT and Sim K between the two groups. The mean PCE was 18.8 ± 8.4 μm in VKC group and 11.7 ± 3.9 μm in control group (P < 0.001). Both KVf and KVb were significantly higher in VKC group when compared to the control group.Conclusion:Children with VKC have significantly higher PCE as measured by Sirius tomographer, and hence, all VKC children should be screened for development of KC and the Sirius tomographer may be an appropriate tool for the same.     

Comparison of central corneal thickness using non-contact tono-pachymeter (Tonopachy) with ultrasound pachymetry in normal children and in children with refractive error

Purpose:To compare the central corneal thickness (CCT) measured by non-contact tono-pachymeter [Tonopachy (TP)] with the gold standard ultrasound pachymetry (UP) in normal children and in children with refractive error.Methods:This cross-sectional study involved 95 normal children (190 eyes) and 123 children with refractive error (246 eyes), a total of 218 children (436 eyes) aged 7-15 years. After refraction and complete ophthalmic evaluation, axial length was measured with IOLMaster 700, CCT was measured with TP followed by UP. The correlation between the CCT measurements obtained with the two methods was analysed by Intraclass correlation coefficient (ICC) and the limits of agreement were assessed with Bland-Altman analysis plot.Results:Mean CCT measured with TP was 537.46 ± 36.41 μm and by UP was 537.17 ± 39.80 μm in normal children (P = 0.79) and in refractive error group, the mean CCT was 533.50 ± 34.91 μm by TP and 531.60 ± 36.30 μm by UP (P = 0.04). The 95% limits of agreement between TP and UP ranged from -19.2 to + 21.6 μm (mean = 1.20) for total children, -20.8 to + 21.4 μm (mean = 0.29) for normal group and -18.0 to + 21.8 μm (mean = 1.90) for refractive error group. ICC for CCT measurement between TP and UP was 0.980 for total children and refractive error group and 0.981 for normal group.Conclusion:The CCT measurement obtained by TP showed an excellent agreement with UP. Hence non-contact TP can be used to assess CCT in children above seven years of age.     

Corneal epithelial thickness analysis of forme fruste keratoconus with optical coherence tomography

AIM:To explore the significance of corneal epithelial thickness analysis in diagnosing early keratoconus.METHODS:There were 26 clinical keratoconus,21 forme fruste keratoconus,40 high corneal astigmatism(ΔK)and 40 low ΔK eyes involved in the study.Fourierdomain optical coherence tomography was used to measure the corneal epithelial thickness of four groups.The morphological features of topographic map and the thickness of corneal epithelial thinnest point were analyzed.The distribution curve of corneal epithelial thickness at 45°,90°,and 135° axial directions that are through the pupil center was also analyzed.One-way ANOVA was performed to compare the data.RESULTS:The topographic map of forme fruste keratoconus corneal epithelial thickness was uniformity shape;crater shape existed only in clinical keratoconus group;and central island shape mainly existed in highΔK group.The thinnest point of corneal epithelial thickness of forme fruste keratoconus group was significantly lower than that of low ΔK group(P=0.022).The thickness of corneal epithelium in the forme fruste keratoconus at 90°was thinner than that in the low astigmatism group at -1,and -2 mm points(P_-1mm=0.015,P_-2mm=0.036).CONCLUSION:The analysis of the thinnest point in forme fruste keratoconus corneal epithelium appears earlier than corneal epithelial remodeling.The topographic map of corneal epithelium in high ΔK eyes appears in central island shape,and can be used for the differential diagnosis of early keratoconus.     

Peripapillary retinal nerve fiber layer thickness in patients with iron deficiency anemia

Purpose:To evaluate the effect of iron deficiency anemia (IDA) on peripapillary retinal nerve fiber layer (RNFL) thickness with optical coherence tomography (OCT).Results:Average ages of 102 patients and 49 control subjects were 35.76 ± 10.112 (range, 18–66) years, and 36.08 ± 8.416 (range, 19–57) years (P = 0.850), respectively. The average RNFL thickness was 94.67 ± 9.380 in the anemia group, and 100.22 ± 9.12 in the control group (P = 0.001). Temporal, nasal, and lower quadrant average RNFL thicknesses of IDA group were thinner than the control group (P = 0.001, P = 0.013, P = 0.008). Upper quadrant RNFL thicknesses in IDA and control groups were similar. Correlation analysis revealed positive correlation between mean RNFL thickness and hemoglobin (r = 0.273), iron (r = 0.177), ferritin (r = 0.163), and transferrin saturations (r = 0.185), while a negative correlation was found between total iron binding capacity (r = −0.199) and mean RNFL thickness.Conclusions:Peripapillary RNFL thickness measured by OCT is thinner in adult female patients with IDA. It may have a significant influence on the management of many disorders such as glaucoma and neuro-ophthalmological diseases.     

Nomogram of peripapillary retinal nerve fiber layer thickness in myopic eyes of north Indian population

Purpose:To evaluate peripapillary-RNFL thickness in myopia by Cirrus OCT among north Indian population by spherical equivalent (SE), age, gender, and axial length (AL).Methods:This was a cross-sectional study held during 2019–2020. Patients aged 18–60 years underwent ophthalmic examination including retinoscopy, AL, and OCT RNFL thickness. Persons with previous ocular surgery or ocular ailment other than refractive error were excluded. The peripapillary-RNFL thickness was noted and compared by demographic determinants.Results:We examined 300 eyes of 300 persons (mean age: 30.75 ± 8.57 years; 144 males/156 females). Among them, 224 were myopes and 76 were emmetropes (EM). The mean SE was − 3.3 ± 0.4D (range: −11.0D to + 0.37D). The mean AL was 24.61 ± 1.92 mm (22.1–29.5). Overall temporal, nasal, superior, inferior, and mean peripapillary-RNFL thickness was 66.31 ± 7.58, 78.57 ± 16.00, 120.63 ± 11.69, 116.60 ± 15.80, and 95.50 ± 10.84 mm, respectively. Temporal, nasal, superior, inferior, and mean peripapillary-RNFL thickness was 73.97 ± 8.36, 94.84 ± 7.63, 127.96 ± 8.96, 136.89 ± 6.53, and 108.34 ± 6.28 mm, respectively, in EM eyes as compared to 63.71 ± 6.18, 73.05 ± 14.24, 118.21 ± 11.53, 109.71 ± 11.50, and 91.14 ± 8.31 mm, respectively, in myopic eyes (P < 0.001). Association of peripapillary-RNFL thickness with myopia and its different grades was P < 0.001. Association of mean peripapillary-RNFL thickness with age was P > 0.005 and gender was P = 0.168. Correlation between SE and RNFL thickness was positive and significant. Correlation between AL and RNFL thickness was negative but statistically significant. Association of AL with SE was P < 0.001.Conclusion:We provide normative peripapillary-RNFL thickness in the north Indian population in order to help in screening for myopia with comorbidity such as glaucoma based on RNFL thickness.     

Semilunar sign of cornea: A multimodal analysis of the posterior corneal opacity in non-infectious anterior scleritis

Purpose:To analyze the morphological outcomes of the posterior corneal opacity or “semilunar sign” in noninfectious anterior scleritis using multimodal imaging.Methods:This was a prospective observational case series. Patients with anterior scleritis from January 2018 to January 2019 were included. Clinical and demographic data were collected. Posterior cornea was visualized using the digital slit lamp photography (Elite, mega digital vision), spectral domain optical coherence tomography (MS39), and specular count analyzer (EM-3000). “Semilunar sign” was defined by the (1) presence of posterior corneal opacity, (2) concave semilunar pattern, (3) absence of blood vessels, and (4) normal anterior cornea. Incidence, clinical characteristics and significance, correlation with Mantoux sensitivity, and role of multimodal valuation were assessed.Results:Overall 76 eyes of 72 patients were recruited with anterior scleritis. Fifteen eyes of 11 patients (15.3%) presented with semilunar sign. The scleritis was both nonnecrotizing (n = 8) and necrotizing (n = 7). The semilunar configuration appeared as isolated (n = 9) and continuous lesion (n = 6). The extent was directly related to the scleral disease extent (P = 0.002). The mean thickness measured 212.5 ± 129.3 mm. The mean central endothelial cell density (ECD) was 2540.8 ± 351.7 cells/mm², which was significantly higher than the involved peripheral cornea (P = 0.05). The mean surface area of the semilunar sign was 7.7 ± 5.2 mm². There was no significant correlation between the opacity thickness and the best-corrected visual acuity (P = 0.895, r = −0.39), ECD (P = 0.52, r = −0.188), and Mantoux (P = 0.696, r =− 0.142)Conclusion:Corneal semilunar sign of scleritis affected the peripheral cornea and caused no functional abnormality in early presentation. Multimodal analysis can aid in clinical assessment and severity.     

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 mm 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.     

Posterior corneal morphological changes in primary congenital glaucoma

Purpose:To compare posterior corneal morphology between older treated and younger untreated children with primary congenital glaucoma (PCG) using anterior segment optical coherence tomography (ASOCT) and intraoperative OCT (iOCT), respectively.Methods: In this comparative study, ASOCT of older PCG children were compared with iOCT of younger untreated PCG patients. Differences between the two groups with respect to posterior corneal morphology were studied.Results: Observed morphological patterns within posterior cornea in older treated (age: 72–300 months) children (87 eyes) included Descemet’s membrane (DM) excrescences (70%), thickened DM (35%), intracameral twin protuberances (92%), and DM detachment (26%). Changes within pre-Descemet’s layer (PDL) (28%) included thickening, breaks, and detachments. Extent of Haab’s striae was associated with thickness of DM/PDL complex (P = 0.008) when analyzed in the treated group. In contrast, in the untreated group (n = 53 eyes, age 1–63 months), posterior corneal changes were limited to diffuse hyper-reflectivity of the DM/PDL complex, with absence of DM tears.Conclusion: Posterior cornea thickens and Haab’s striae become more circumscribed in eyes of older treated children compared to untreated PCG eyes, probably reflecting a healing response of posterior cornea over time.     

Corneal endothelial cell density and microvascular changes of retina and optic disc in autosomal dominant polycystic kidney disease

Purpose:Vascular endothelial dysfunction in autosomal dominant polycystic kidney disease (ADPKD) may affect the retinal vascular parameters due to structural similarities of kidney and retina. We aimed to evaluate the microvascular changes of retina and optic disc and also corneal endothelial cell density in patients with ADPKD.Methods:Forty-six eyes of 23 patients with ADPKD (Group 1), and 46 eyes of 23 sex- and age-matched healthy controls (Group 2) were included in this cross-sectional study. Demographic and ophthalmic findings of participants were collected. Corneal endothelial cell density (CECD) measurements were obtained by noncontact specular microscopy. Foveal retinal thickness, peripapillary retinal nerve fiber layer (RNFL) thickness, vessel density in different sections of the retina and optic nerve head were analyzed by optical coherence tomography angiography.Results:The mean ages were 41 ± 11 years for Group 1 and 39 ± 10 years for Group 2 (P = 0.313). CECD values were significantly lower in group 1 when compared to group 2 (2653 ± 306 cells/mm² and 2864 ± 244 cells/mm², respectively, P < 0.001). The foveal retinal thickness and RNFL thickness were similar, but superior quadrant thickness of RNFL was significantly lower in Group 1 than Group 2 (126 ± 14 μm vs. 135 ± 15 μm, P = 0.003). In Group 1, whole image of optic disc radial peripapillary capillary densities were significantly lower compared to Group 2 (49.4 ± 2.04%, and 50.0 ± 2.2%, respectively, P = 0.043). There was no significant difference regarding superficial, deep retinal vessel densities, foveal avascular zone and flow areas between the groups (P > 0.05 for all).Conclusion:Lower CECD values and decreased superior quadrant RNFL thickness, and microvascular densities of optic disc were revealed in patients with ADPKD. Evaluation of CECD and retinal microvasculature may be helpful in the management of these patients.     

Evaluation of the White-to-White Distance in 39,986 Chinese Cataractous Eyes

PurposeTo investigate the distribution of white-to-white (WTW) distance and its associations with other biometric parameters in Chinese cataractous eyes.MethodsData on 39,986 eyes from 23,627 Chinese cataract patients were analyzed. Ocular biometric parameters, including WTW distance, corneal curvature, anterior chamber depth (ACD), lens thickness (LT), central corneal thickness (CCT), and axial length (AL), were obtained using the ZEISS IOLMaster 700.ResultsThe mean age of patients was 63.7 ± 12.4 years, and 57.61% were female. The mean WTW distance was 11.69 ± 0.46 mm. The WTW distance was larger in male patients than in female patients for all age groups (all P < 0.001). The WTW distance was positively correlated with corneal curvature and ACD and negatively correlated with age, LT, and CCT (all P < 0.001). Multivariable analysis revealed that a larger WTW distance was associated with younger age; male gender; larger corneal curvature, ACD, and LT; and thinner CCT (all P < 0.001). Notably, the association between WTW distance and AL was not linear. As the AL increased, the WTW distance initially increased, reached a peak in the group with ALs of 24.5 to 26 mm, and then slowly decreased. However, all of the myopic eyes (AL > 24.5 mm) still had larger WTWs than the normal and short eyes (AL ≤ 24.5 mm).ConclusionsIn Chinese cataractous eyes, the WTW distance was larger in younger male patients with flatter corneas, deeper anterior chambers, thicker lenses, and thinner central corneas. The association between WTW distance and AL was not linear, and WTW distance was the largest in eyes with ALs of 24.5 to 26 mm.     

The influence of routine uncomplicated phacoemulsification on the orthogonality of the cornea

Purpose:The aim of this study was to determine the effect of routine uncomplicated phacoemulsification on the orthogonal distribution of mass within the central optical zone of the cornea.Methods:Astigmatism at both corneal surfaces was evaluated using Orbscan II (Bausch &and Lomb) before and up to 3 months after routine phacoemulsification (one eye/patient). The data were subjected to vector analysis to estimate the pre-and postoperative total astigmatism of the cornea (TCA).Results:Reporting the chief findings in minus cylinder (diopters, DC) over the central 3 mm (A) and 5 mm (B) optical zones. Mean TCA powers (±sd) at pre- and 3-months postop were A) –4.45DC (±2.00) and –5.69DC (±2.69), B) –2.91DC (±2.22) and –2.71DC (±1.60). Change in mean power was significant over 3 mm (P < 0.01, n = 49) but not over 5 mm. Inter-zonal differences were significant (P < 0.01). There was a significant linear relationship between the change in TCA power (y = preoperative-postoperative) and TCA at preoperative stage (x) where, A) y = 0.45x + 3.12 (r = 0.336, n = 49, P = 0.018), B) y = x + 2.65 (r = 0.753, n = 49, P = <0.01). Over the central 3 mm zone only, change (preoperative-postoperative) in axis (°) of TCA (y₁) was significantly associated with TCA axis at preoperative stage (x₁) where y₁ = 1.391x₁-0.008x₁²-0.701 (r = 0.635, n = 49, P < 0.01).Conclusion:Changes in TCA power and axis at 3 months postop, determined using Orbscan II, are indicative of orthogonal alterations in the distribution of corneal tissue. Over the central 3 mm zone, the association between y₁ and x₁ shows that a change in TCA axis is more profound when preoperative axis is near 90° i.e., against-the-rule.