Stabilization of refractive error and associated factors following small incision phacoemulsification cataract surgery

Background Accumulating evidence suggests that refractive stabilization occurs rapidly following small incision cataract surgery. Nonetheless, many guidelines still suggest waiting four to 6 weeks before prescribing corrective lenses. This study was undertaken to supplement the existing literature regarding refractive stabilization, and evaluate multiple contributing factors that could dissuade clinicians from confidently correcting refractive error in the early post-operative course following routine cataract surgeries. Methods Adult patients undergoing phacoemulsification cataract surgery with uncomplicated surgeries and post-surgical courses at the Calgary Ophthalmology Centre (Calgary, Alberta, Canada) were included in this prospective observational case series. Exclusion criteria included known corneal dystrophies, infectious keratitis, complicated surgery or toric/multifocal IOLs. Data was collected at weekly intervals for a total of 6 weeks. Collected data included autorefraction, visual acuity, corneal pachymetry, and effective lens position. Results One hundred six eyes of 104 patients were included in this study. Post-operative sphere, cylinder and spherical equivalent were not significantly different at any post-operative week compared with week six, and 80–86% of patients were within 0.5D of last follow-up spherical equivalent at any week. The secondary outcomes of central corneal thickness, effective lens position and visual acuity did, however, exhibit significant differences between early post-operative weeks and last follow-up values. Conclusions These data suggest that refractive error can be effectively measured and corrected as early as one-week post-operatively in the majority of patients, though other measures of post-operative stability including central corneal thickness, effective lens position and visual acuity can require up to 4 weeks to stabilize. Thus a conservative and pragmatic approach may be to wait until 4 weeks post-operatively prior to obtaining refractive correction following uncomplicated phacoemulsification cataract surgery.

Predictive factors of the accelerated transepithelial corneal cross-linking outcomes in keratoconus

Background This study aimed to evaluate the clinical outcomes and assess preoperative characteristics that may predict outcomes in keratoconus 1 year after accelerated transepithelial corneal cross-linking (ATE-CXL). Methods This prospective study included 93 eyes of 84 consecutive keratoconus patients with 1-year follow-up after ATE-CXL. Preoperative characteristics included corneal astigmatism, anterior chamber depth, anterior chamber volume, radius of curvature, posterior elevation, central corneal thickness (CCT), thinnest corneal thickness, steepest meridian keratometry, flattest meridian keratometry, and the maximum keratometry (Kmax). Data were obtained preoperatively and at 1, 3, 6, and 12 months postoperatively. The patient eyes were grouped into 3 subgroups according to CCT and Kmax values to observe the changes of keratoconus progression. Results All patients were successfully operated without complications at any follow-up time point. Mean changes of Kmax from baseline at 6 and 12 months were − 0.60 ± 2.21 D (P = 0.011) and − 0.36 ± 1.58 D (P = 0.030), respectively. Eyes with a thinner CCT and higher Kmax values exhibited a tendency for topographic flattening of ≥1.0 D (P = 0.003; P = 0.003). In the subgroup comparison, the Kmax values decreased significantly at 6 and 12 months after ATE-CXL in the group with CCT ≤ 450 μm (P = 0.018 and P = 0.045); the Kmax values of the group with Kmax > 65.0 D decreased significantly at 6 months postoperatively (P = 0.025). Conclusion ATE-CXL is a safe and effective treatment for keratoconus patients. Patients with thinner CCT and higher Kmax values are more likely to benefit from ATE-CXL.

Evaluation of the B/F Ratio Distribution of Cataract Patients Without Corneal Abnormalities and Its Effect on Ocular Parameters

Purpose: To evaluate the distribution of the posterior-anterior corneal radius ratio (B/F ratio; posterior corneal radius/anterior corneal radius) in patients without corneal abnormalities, and to investigate which parameters affect this ratio. Methods: Five thousand eyes from 5,000 patients who underwent cataract surgery were recruited to this study. We explored the linear relationship between B/F ratio and 13 variables using Principal Component-Multivariate Linear Regression Analysis. Results: The B/F ratio was negatively correlated with the difference between simulated keratometry (SimK) and true net power (TNP), central corneal thickness, spherical aberration (SA), and posterior corneal astigmatism and positively correlated with posterior corneal radius, corneal posterior surface, axial length (AL) and anterior corneal radius. Several variables (central corneal thickness, difference between SimK and TNP and asphericity coefficient (Q-value) of the posterior corneal surface) had the highest loading on the final score. B/F ratio reflects the refractive state and anatomical structure of the cornea: thus, higher B/F ratios were associated with larger posterior corneal surface curvature radius, longer axial length, thinner central corneal thickness, lower high order aberrations of the cornea and SA, and the numerical difference between simK and TNP gradually reduced. In clinical practice, for patients with lower B/F ratio, special care should be taken in the choice of system used for intraocular lens (IOL) measurements.

OCULAR CLINICAL PROFILE OF PATIENTS WITH PSEUDOEXFOLIATION SYNDROME AND PSEUDOEXFOLIATION GLAUCOMA AT TERTIARY CARE CENTRE IN KASHMIR

Aim: To study the clinical profile of pseudoexfoliation (PEX) syndrome and Pseudoexfoliation glaucoma at tertiary care centre in Kashmir. Materials and Methods: A cross sectional study consisting of 100 PEX and 100 PEXG patiens, attending the general ophthalmology clinic of a tertiary care center in kashmir. All patients underwent a complete ophthalmologic evaluation including recording IOP,gonioscopy and Central Corneal Thickness(CCT). Results: The study cohort comprised 200 patients(100 with PEX and 100 with PEXG). There were 145(72.5) males and 55(27.5%) females. The highest number of patients (120 patients) were from the age group between 61 and 70years. 145(72.5%) patients were involved in outdoor activities.153(76.5%) patients had bilateral involvement of pseudoexfoliationand pseudoexfoliative material was present at anterior lens capsule in 175(49.58%) eyes. Nuclear cataract was predominant type of cataract and was present in 188(48.2%)eyes. Mean IOP was 17.26±7.634mmHg in PEX group and 24.39±4.456mmHg in PEXG group. Gonioscopyshowed open angles in 96.5% of eyes and occludable in 3.5% eyes . Mean central corneal thickness was 531.80±19.127μm. Conclusion: The prevalence of PEX is found to increase with age. Patients with PXG had more severity of optic nerve damage at presentation. Therefore a careful assessment for detection of PEX is warranted and regular follow-up of patients is desired to minimize the extent of optic nerve damage.

Analysis of Lens Thickness Distribution Based on Swept-Source Optical Coherence Tomography (SS-OCT)

Objective. This study aimed to analyze the distribution of lens thickness (LT) and its associations in age-related cataract patients based on swept-source optical coherence tomography (SS-OCT). Methods. This cross-sectional study included 59,726 Chinese age-related cataract patients. Only right-eye data were included in the study. Repeated measures of ocular parameters were performed using an IOL Master 700 device. The distributions of ocular biometric data including anterior chamber depth (ACD), LT, axial length (AL), central corneal thickness (CCT), white-to-white (WTW), and mean keratometry (MK) and their associations with age were assessed. The anterior segment (AS) was measured as the sum of CCT, ACD, and LT, while the vitreous chamber depth (VCD) was calculated as the difference between AL and AS. The values of LT : AL, AS : AL, and VCD : AL in different AL groups and their changes are the main outcome measures used to observe the proportion of the anterior and posterior segments of the eye. Results. Biometric data were available for 59,726 individuals. The mean age was 68.81 years (range = 40–100); 40.62% were male and 59.38% were female. Mean anterior chamber depth (ACD) was 3.02 ± 0.44 mm, mean LT was 4.51 ± 0.44 mm, mean axial length (AL) was 23.89 ± 1.92 mm, mean central corneal thickness (CCT) was 0.53 ± 0.03 mm, mean white-to-white (WTW) was 11.64 ± 0.44 mm, and mean keratometry (MK) was 44.27 ± 1.65 diopter. Female patients had shorter AL, shallower ACD, smaller CCT and WTW, decreased LT, and steeper corneas ( p < 0.005). ACD revealed the strongest negative correlation ( p ≤ 0.001, r = –0.682) with LT. Age ( p ≤ 0.001, r = 0.348) showed a moderate positive correlation, whereas MK ( p ＜ 0.05, r = 0.011), CCT ( p ≤ 0.001, r = 0.041) had a weak positive correlation and WTW ( p ≤ 0.001, r = –0.034) had a weak negative correlation with LT. A nonlinear correlation was found between LT and AL. LT increased with age in both males and females. LT changed variably in eyes with AL less than 27 mm, LT decreased as AL increased, then LT gradually increased as AL increased in extremely long and extra-long eyes ( p ≤ 0.001). LT : AL and AS : AL decreased as AL increased, VCD : AL gradually increased as AL increased in highly myopic eyes, and VCD : AL increased by about 0.01 for every 1 mm increase in AL. Conclusions. Among Chinese age-related cataract patients, we found LT to have the strongest relation with ACD. The lens was thicker in elderly patients and women. The correlation between LT and AL is not a simple negative correlation; with the increase of age, LT decreases first and then increases. The proportion of VCD is constantly rising with the elongation of AL.

Relationship of Central Corneal Thickness with the Status of Diabetic Retinopathy and Level of HbA1C in Diabetic Patients

Study Objectives: To determine the relationship of central corneal thickness with the status of diabetic retinopathy and level of HbA1c in diabetic patients. Study Design and Settings: Department of Ophthalmology, Allied Hospital/DHQ Hospital, Faisalabad Pakistan from Jan 2021 to June 2021. Patients and Methods: Out of the patients visiting OPD, 100 patients with clinically diagnosed type 2 DM which satisfied the range of selected standards and offered written informed agreement were involved in the research with the use of simple random sampling. Snellen’s visual acuity chart for distance vision and Jaeger’s chart for near vision were used to determine the best-corrected visual acuity. Wet Refraction and axial length was measured using A-scan. Goldmann applanation tonometry was used to measure the intraocular pressure. Results of the Study: In this research sixty two percent of the patients were men and thirty eight percent patients were women. Total 84 patients had type 2 DM of duration 5-10 years, and the remaining 16 patients had diabetes for over 10 years. Total 35 patients had HbA1c between 4-5.6%, 31 patients had HbA1c between 5.7- 6.5% and 34 patients had HbA1c ≥ 6.5%. From 100 patients with Diabetes Mellitus Type 2, 21 patients had no diabetic retinopathy, 28 patients had very minor and minor NPDR, 25 patients had average NPDR, 19 patients had critical and very acute NPDR and 7 patients had PDR. The mean HbA1c in patients with no diabetic retinopathy was 5.05%. The mean HbA1c in patients having minor and very little NPDR remained 5.64%. The mean HbA1c in patients with moderate NPDR was 6.36%. The mean HbA1c in patients with critical and very acute NPDR was 8.26%. The mean HbA1c in patients with severe PDR was 9.86%. This was a statistically significant survey (P-value = 0.01). Conclusion: This study showed a strong correlation between the central corneal thickness to the severity of diabetic retinopathy and HbA1c levels emphasizes the importance of evaluation of corneal endothelial morphology in the early screening and diagnosis of microvascular complications of DM Keywords: Central Corneal Thickness, Diabetic Retinopathy, HbA1c

Preliminary Characterization of Predictive Factors of the Visual Change after Epi-On and Epi-Off Corneal Collagen Crosslinking Techniques

Purpose. To investigate the potential predictive factors of the visual change achieved with accelerated epi-on and epi-off corneal collagen crosslinking (CXL) in keratoconus. Methods. This retrospective comparative study analyzed 67 eyes treated with an accelerated epithelium-on (epi-on group) and epithelium-off (epi-off group) CXL. The clinical outcomes were evaluated and compared during a 1-year follow-up. Likewise, the relationship of the change achieved with both CXL techniques in the corrected distance visual acuity (CDVA) with different preoperative data was investigated. Results. The mean CDVA change at 3 months postoperatively was −0.04 ± 0.19 and −0.07 ± 0.25 in the epi-on and epi-off groups, respectively ( p = 0.809). In the epi-on group, this change was significantly correlated with the preoperative apical (r = −0.375, p = 0.045) and central corneal thickness (r = −0.402, p = 0.031). In the epi-off group, the CDVA change was significantly correlated with not only the preoperative apical (r = 0.402, p = 0.028) and central corneal thickness (r = 0.367, p = 0.046) but also with some topometric and aberrometric indices (r ≤ −0.374, p ≤ 0.042). Furthermore, the change in CDVA in the epi-on group could be predicted from age, preoperative refractive astigmatism J45 component, anterior corneal asphericity, and posterior corneal high order aberration root mean square ( p = 0.002, R2 = 0.503). In the epi-off group, the CDVA change could be predicted from the preoperative minimum corneal thickness and magnitude of the vertical anterior corneal primary coma component ( p = 0.001, R2 = 0.446). Conclusions. Clearly, different predictive factors of the visual change induced with the accelerated epi-on and epi-off CXL techniques are present, suggesting a different mechanism of action for stiffening the cornea and inducing changes in this structure.