Dilraj S. Grewal

Corneal collagen crosslinking using riboflavin and ultraviolet-A light for keratoconus

PURPOSE: To evaluate changes in corneal curvature, corneal elevation, corneal thickness, lens density, and foveal thickness after corneal collagen crosslinking with riboflavin and ultraviolet‐A (UVA) light in eyes with progressive keratoconus. SETTING: Grewal Eye Institute, Chandigarh, India. METHODS: Subjective refraction, best corrected visual acuity (BCVA), Scheimpflug imaging, and optical coherence tomography were performed preoperatively and 1 week, 1, 3, and 6 months, and 1 year after crosslinking. RESULTS: There were no significant differences (P > 0.05) in mean values between preoperatively and 1 year postoperatively, respectively, in BCVA (0.22 ± 0.10 and 0.20 ± 0.10), spherical equivalent (−6.30 ± 4.50 diopters (D) and −4.90 ± 3.50 D), or cylinder vector (1.58 × 7° ± 3.8 D and 1.41 × 24° ± 3.5 D). There was no significant difference in mean measurements between preoperatively and 1 year postoperatively, respectively, for central corneal thickness (458.9 ± 40 μm and 455.2 ± 48.6 μm), anterior corneal curvature (50.6 ± 7.4 D and 51.5 ± 3.6 D), posterior corneal curvature (−7.7 ± 1.2 D and −7.4 ± 1.1 D), apex anterior (P = .9), posterior corneal elevation (P = .7), lens density (P = .33), or foveal thickness (175.7 ± 35.6 μm and 146.4 ± 8.5 μm; P = .1). CONCLUSIONS: Stable BCVA, spherical equivalent, anterior and posterior corneal curvatures, and corneal elevation 1 year after crosslinking indicate that keratoconus did not progress. Unchanged lens density and foveal thickness suggest that the lens and macula were not affected after UVA exposure during crosslinking.

Evaluation of subconjunctival bevacizumab as an adjunct to trabeculectomy a pilot study.

PURPOSE To determine whether bevacizumab can reduce bleb failure in patients undergoing first-time trabeculectomy for primary open-angle glaucoma (POAG) or chronic angle-closure glaucoma (CACG). DESIGN Nonrandomized, open-label, prospective, interventional case series. PARTICIPANTS Twelve individuals (7 males; 5 females) with a diagnosis of POAG or CACG, a recorded intraocular pressure (IOP) of more than 21 mmHg (between 10 am and 12 pm), glaucomatous damage on visual field or optic disc, and taking a maximum tolerated dose of IOP-lowering medication. INTERVENTION Unilateral trabeculectomy with subconjunctival injection of bevacizumab (0.05 ml, 1.25 mg) adjacent to the bleb using a 30-gauge needle and tuberculin syringe administered immediately after trabeculectomy. MAIN OUTCOME MEASURES Treatment success (unmedicated IOP of 6 to 16 mmHg inclusive) at 6 months; bleb characteristics according to the Moorfields bleb grading system on days 1, 7, 30, 90, and 180; incidence of postoperative intervention with 5-fluorouracil or mitomycin C; bleb needling; and incidence of and time to surgical failure. RESULTS Mean age was 54.6+/-13.6 years. The mean preoperative IOP was 24.4+/-7.1 mmHg (range, 12-44 mmHg) and the patients were taking an average of 2.7+/-1.6 IOP-lowering medications (range, 1-4). The mean postoperative IOP was 8+/-3.1 mmHg (range, 4-13 mmHg) on day 1, 9.4+/-2.7 mmHg (range, 6-14 mmHg) on day 7, 10.9+/-2.8 mmHg (range, 8-16 mmHg) at 1 month, 10.3+/-2.5 mmHg (range, 7-14 mmHg) at 3 months, and 11.6+/-2.2 mmHg (range, 8-14 mmHg) at 6 months follow-up with no IOP-lowering medications. Preoperative best-corrected visual acuity was 0.70+/-0.3, whereas at 6 months after trabeculectomy, it was 0.66+/-0.3 (P = 0.39). After a mean follow-up of 182 days, of the 12 eyes, a successful trabeculectomy with respect to IOP control was observed in 11 eyes (92%), with an average IOP reduction of 52%. CONCLUSIONS In this pilot study with a small number of subjects, 6-month outcomes suggest that subconjunctival bevacizumab is a potential adjunctive treatment for reducing the incidence of bleb failure after trabeculectomy. FINANCIAL DISCLOSURE(S) The authors have no proprietary or commercial interest in any materials discussed in this article.

Diagnostic Ability of Fourier-Domain vs Time-Domain Optical Coherence Tomography for Glaucoma Detection

PURPOSE To compare retinal nerve fiber layer (RNFL) thickness assessments and the discriminating ability of Fourier-domain optical coherence tomography (FD-OCT) with that of time-domain optical coherence tomography (TD-OCT) for glaucoma detection. DESIGN Prospective, nonrandomized, observational cohort study. METHODS Normal and glaucomatous eyes underwent complete examination, standard automated perimetry, optic disc photography, TD-OCT (Stratus OCT; Carl Zeiss Meditec, Dublin, California, USA), and FD-OCT (RTVue; Optovue Inc, Fremont, California, USA). One eye per subject was enrolled. Two consecutive scans were acquired using a 3.46-mm diameter scan with TD-OCT and a 3.45-mm diameter scan with FD-OCT. For each of 5 RNFL parameters, the area under the receiver operator characteristic curve was calculated to compare the ability of FD-OCT and TD-OCT to discriminate between normal and glaucomatous eyes. RESULTS Fifty healthy persons (mean age, 65.3 +/- 9.9 years) and 50 glaucoma patients (mean age, 67.7 +/- 10.5 years) were enrolled. Average, superior, and inferior RNFL thickness measurements (in micrometers) were significantly (P < .01) greater with FD-OCT compared with TD-OCT in normal eyes (103.3 +/- 12.6 vs 96.3 +/- 10.7, 134.5 +/- 18.6 vs 113.9 +/- 16.3, and 129.7 +/- 16.9 vs 125.5 +/- 15.8, respectively) and glaucomatous eyes (P < .001; 77.6 +/- 17.6 vs 70.4 +/- 18.6, 108.0 +/- 26.8 vs 86.8 +/- 30.2, 82.2 +/- 3.3 vs 73.5 +/- 26.1, respectively). The area under the receiver operator characteristic curves for RNFL thickness were similar (P > .05) using FD-OCT (average, 0.88; superior, 0.80; inferior, 0.94) and TD-OCT (average, 0.87; superior, 0.79; inferior, 0.95). CONCLUSIONS Cross-sectional peripapillary RNFL thickness measurements obtained using FD-OCT generated with the RTVue are greater than those obtained with TD-OCT and have similar diagnostic performance for glaucoma detection.

Diagnosis of glaucoma and detection of glaucoma progression using spectral domain optical coherence tomography.

Purpose of review With the rapid adoption of spectral domain optical coherence tomography (SDOCT) in clinical practice and the recent advances in software technology, there is a need for a review of the literature on glaucoma detection and progression analysis algorithms designed for the commercially available instruments. Recent findings Peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness, including segmental macular thickness calculation algorithms, have been demonstrated to be repeatable and reproducible, and have a high degree of diagnostic sensitivity and specificity in discriminating between healthy and glaucomatous eyes across the glaucoma continuum. Newer software capabilities such as glaucoma progression detection algorithms provide an objective analysis of longitudinally obtained structural data that enhances our ability to detect glaucomatous progression. RNFL measurements obtained with SDOCT appear more sensitive than time domain OCT (TDOCT) for glaucoma progression detection; however, agreement with the assessments of visual field progression is poor. Summary Over the last few years, several studies have been performed to assess the diagnostic performance of SDOCT structural imaging and its validity in assessing glaucoma progression. Most evidence suggests that SDOCT performs similarly to TDOCT for glaucoma diagnosis; however, SDOCT may be superior for the detection of early stage disease. With respect to progression detection, SDOCT represents an important technological advance because of its improved resolution and repeatability. Advancements in RNFL thickness quantification, segmental macular thickness calculation and progression detection algorithms, when used correctly, may help to improve our ability to diagnose and manage glaucoma.

Correlation of nuclear cataract lens density using Scheimpflug images with Lens Opacities Classification System III and visual function.

PURPOSE To calculate the average lens density (ALD) and nuclear lens density (NLD) using Scheimpflug images and to determine their correlation with logarithmic minimal angle resolution (logMAR) best-corrected visual acuity (BCVA), contrast sensitivity (CS), and lens grading based on the Lens Opacities Classification System (LOCS) III. DESIGN Cross-sectional observational study. PARTICIPANTS One hundred ten patients with age-related nuclear cataract. METHODS The logMAR BCVA was recorded using Early Treatment Diabetic Retinopathy Study charts and photopic contrast-sensitivity using CSV-1000LV (Vector Vision, Greeneville, OH). Fifty Scheimpflug images (Pentacam, Oculus, Germany) covering 360 degrees of the lens were obtained for 1 eye of each patient after dilation. All Scheimpflug images were exported to ImageJ software (NIH, Bethesda, MD) for analysis wherein the ALD and NLD (using a mask applied to the lens nuclear area) were calculated in pixel-intensity units. Repeatability was determined using coefficient of variation (CoV) and intraclass correlation coefficient (ICC). Lens opacity on slit-lamp images was graded using LOCS III for nuclear opalescence (NO) and nuclear color (NC). MAIN OUTCOME MEASURES We evaluated ALD and NLD on Scheimpflug images and their correlation with NO and NC LOCS III grading, BCVA, and photopic CS. RESULTS The ICC for ALD and NLD were 0.983 and 0.99, respectively; the CoV were 3.92+/-1.76% and 2.57+/-0.74%, respectively. The ALD correlated with NO (r = .774; P<0.001), NC (r = .732; P<0.001), BCVA (r = 0.696; P<0.001), and CS at 3 cycles per degree CPD (P = 0.011), 6, 12, and 18 CPD (P<0.001). The NLD correlated with NO (r = .859; P<0.001), NC (r = .81; P<0.001), BCVA (r = .760; P<0.001), CS at 3 CPD (P = 0.002), 6, 12, and 18 CPD (P<0.001). The NLD had a significantly stronger correlation with BCVA (P<0.05), NO (P<0.01), NC (P<0.01), and CS at 6 CPD (P<0.01) and 12 CPD (P<0.005) compared with ALD. CONCLUSIONS Repeatable 360 degrees lens density measurements were obtained using Scheimpflug imaging. A stronger correlation was observed between NLD and LOCS III grading, BCVA, and photopic CS than with ALD. The NLD is an objective and repeatable method for assessment of lens density, which could be helpful in longitudinal studies monitoring nuclear cataracts.

Visual and anatomical outcomes following intravitreal aflibercept in eyes with recalcitrant neovascular age-related macular degeneration: 12-month results

PurposeTo describe the efficacy of intravitreal aflibercept on 12-month visual and anatomical outcomes in patients with neovascular age-related macular degeneration (AMD) recalcitrant to prior monthly intravitreal bevacizumab or ranibizumab.MethodsNon-comparative case series of 21 eyes of 21 AMD patients with evidence of persistent exudation (intraretinal fluid/cysts, or subretinal fluid (SRF), or both) on spectral domain OCT despite ≥6 prior intravitreal 0.5 mg ranibizumab or 1.25 mg bevacizumab (mean 29.8±17.1 injections) over 31.6±17.4 months who were transitioned to aflibercept.ResultsAt baseline, best-corrected visual acuity (BCVA) was 0.42±0.28 logarithm of minimum-angle of resolution (logMAR), central foveal thickness (CFT) was 329.38±102.67 μm and macular volume (MV) was 7.71±1.32 mm3. After 12 months of aflibercept (mean 10.2±1.2 injections), BCVA was 0.40±0.28 logMAR (P=0.5), CFT decreased to 292.71±91.35 μm (P=0.038) and MV improved to 7.33±1.27 mm3 (P=0.003). In a subset of 15 eyes with a persistent fibrovascular or serous pigment epithelial detachment (PED), mean baseline PED greatest basal diameter (GBD) was 2350.9±1067.6 μm and mean maximal height (MH) was 288.7±175.9 μm. At 12 months, GBD improved to 1896.3±782.3 μm (P=0.028), while MH decreased to 248.27±146.2 μm (P=0.002).ConclusionIn patients with recalcitrant AMD, aflibercept led to anatomic improvement at 12 months, reduction in proportion of eyes with SRF and reduction in PED, while preserving visual acuity.

Assessment of central corneal thickness in normal, keratoconus, and post-laser in situ keratomileusis eyes using Scheimpflug imaging, spectral domain optical coherence tomography, and ultrasound pachymetry.

PURPOSE: To compare the central corneal thickness (CCT) in normal eyes, eyes with keratoconus, and eyes after laser in situ keratomileusis (LASIK) using 3 methods. SETTING: Cornea Clinic, Grewal Eye Institute, Chandigarh, India. METHODS: In this study, CCT was measured by sequential Scheimpflug imaging, spectral‐domain anterior segment optical coherence tomography (AS‐OCT), and ultrasound (US) pachymetry. RESULTS: Each of the 3 groups comprised 50 eyes. There were no differences between the 3 groups in age, sex, or intraocular pressure. In normal eyes, CCT was statistically significantly higher by US pachymetry (mean 525.8 μm ± 41.4) [SD] than by Scheimpflug imaging (mean 519.4 ± 40.9 μm) and AS‐OCT (mean 517.9 ± 41.5 μm) (both P<.001). In keratoconus eyes, CCT by US pachymetry (mean 446.4 ± 57.9 μm) was statistically significantly higher than by Scheimpflug imaging (mean 439.6 ± 62.1 μm) (P = .002) and AS‐OCT (mean 441.8 ± 58.4 μm) (P = .007). In post‐LASIK eyes CCT by US pachymetry (mean 462.4 ± 44.7 μm) was significantly higher than by Scheimpflug imaging (mean 457.9 ± 33.6 μm) (P = .012) and AS‐OCT (mean 455.4 ± 43.2 μm) (P<.001). In all groups, CCT measured by Scheimpflug imaging and AS‐OCT was similar. CONCLUSIONS: There was a statistically significant difference between Scheimpflug imaging and US pachymetry and AS‐OCT, with US pachymetry measurements being consistently thicker. Thus, CCT should be interpreted in the context of the instrument used. Financial disclosure: No author has a financial or proprietary interest in any material or method mentioned.

Reversal of Retinal Ganglion Cell Dysfunction after Surgical Reduction of Intraocular Pressure

PURPOSE The pattern electroretinogram optimized for glaucoma screening (PERGLA) is a noninvasive method of objectively measuring retinal ganglion cell (RGC) function. This study was undertaken to quantify the RGC response to intraocular pressure (IOP) reduction after glaucoma surgery. DESIGN Prospective cohort study. PARTICIPANTS Forty-seven eyes of 47 patients with uncontrolled IOP or progressive glaucomatous optic neuropathy receiving maximal medical therapy requiring trabeculectomy or aqueous drainage device implantation who met eligibility criteria. METHODS Eyes with visual acuity less than 20/30, corneal or retinal pathologic features, or unreliable standard automated perimetry (SAP) results were excluded. All patients underwent complete ocular examination, arterial blood pressure, SAP, and PERGLA at 2 sessions before surgery and at 3 months after surgery. Mean ocular perfusion pressure (MOPP) was calculated. Each measure of PERGLA amplitude and phase was an average of 600 artifact-free signal registrations. MAIN OUTCOME MEASURES Intraocular pressure and PERGLA amplitude and phase. RESULTS Forty-seven eyes of 47 patients (mean age ± standard deviation [SD], 69.9 ± 11.3 years) were enrolled. Thirty-four eyes (72%) underwent trabeculectomy with antifibrosis therapy; 13 eyes (28%) underwent glaucoma drainage implant surgery. Mean ± SD postoperative IOP (10.4 ± 4.6 mmHg) was significantly (P< 0.001) reduced compared with that before surgery (19.7 ± 8.6 mmHg). Mean ± SD postoperative PERGLA amplitude (0.46 ± 0.22 μV) was significantly (P = 0.001) increased compared with preoperative PERGLA amplitude (0.37 ± 0.18 μV). Mean ± SD postoperative PERGLA phase (1.72 ± 0.20 π-radian) was significantly (P = 0.01) reduced compared with preoperative PERGLA phase (1.81 ± 0.22 π-radian). Mean ± SD postoperative MOPP (53.1 ± 6.4 mmHg) was significantly (P < 0.001) increased compared with mean ± SD preoperative MOPP (45.8 ± 10.1 mmHg). No correlation (P > 0.05) was identified between change in PERGLA amplitude and change in IOP or MOPP. CONCLUSIONS Reversal of RGC dysfunction occurs after surgical reduction of IOP and may be quantified using PERGLA.

Autoimmune retinopathy and antiretinal antibodies: a review.

Purpose: To review the current state for diagnosis and management of autoimmune retinopathy. Methods: A review of the literature was performed, encompassing autoimmune retinopathy including paraneoplastic retinopathy (cancer-associated retinopathy, melanoma-associated retinopathy, and bilateral diffuse uveal melanocytic proliferation) and non-paraneoplastic autoimmune retinopathy. Based on this review, current principles and techniques for diagnosis and the treatments reported for autoimmune retinopathy are discussed with the aim to clarify some of the confusion that exists regarding this complex entity. Results: Autoimmune retinopathy encompasses a spectrum of retinal degeneration phenotypes. The clinical features, fundus characteristics, and electroretinogram findings for paraneoplastic and non-paraneoplastic retinopathy are reviewed. The different antiretinal antibodies reported in these entities are described. The diagnostic approaches for detecting these antiretinal antibodies and their limitations are covered. The treatments reported for autoimmune retinopathy and their outcomes are reviewed. Conclusion: Among the myriad of antiretinal antibodies reported, challenges persist in determining which antibodies are pathogenic and which are benign and what factors cause antiretinal antibodies to become pathologic. There also remain difficulties in the detection and accurate measurement of antiretinal antibodies, and the response to therapeutic intervention in autoimmune retinopathy is variable.

Pentacam Tomograms : A Novel Method for Quantification of Posterior Capsule Opacification

PURPOSE To develop and validate a method to quantify posterior capsule opacification (PCO) in eyes after cataract surgery and intraocular lens implantation using Scheimpflug Pentacam tomograms and compare its validity with slit lamp retroillumination image analysis. METHODS One hundred twenty-four pseudophakic eyes of 124 patients were divided into two groups. Group 1 consisted of 40 eyes with visually significant PCO, and group 2 consisted of 84 eyes without visually significant PCO. Pentacam Imaging was performed after full mydriasis using the 50-scan acquisition protocol, and high-resolution tomograms were reconstructed and analyzed using ImageJ freeware. Retroillumination photographs were captured for group 1 eyes using the Topcon digital slit lamp, and these were analyzed using POCOman software to calculate an aggregate severity grade and percentage PCO value. Correlation coefficients were calculated for PCO values obtained using POCOman and ImageJ. RESULTS Mean PCO percentage value obtained using POCOman software was 23.34 +/- 6.25 U, mean aggregate PCO severity grade was 0.46 +/- 0.28 U, and mean pixel-intensity value using ImageJ was 31.071 +/- 8.26 U. There was a significant positive correlation between the percentage PCO (P = 0.000; r = 0.864) and PCO severity grade (P = 0.001; r = 0.490) obtained for group 1 eyes using slit lamp retroillumination images and PCO pixel intensity obtained using Pentacam tomograms. CONCLUSIONS Retroillumination photographs are the standard for quantifying PCO. Pentacam tomograms are easier to obtain and are free of flash reflections, and they allow for a more objective analysis. The correlation between the two methods demonstrates that ImageJ analysis of Pentacam tomograms is a viable tool for PCO analysis.