Evaluation of an offline, artificial intelligence system for referable glaucoma screening using a smartphone-based fundus camera: a prospective study.

BACKGROUND/OBJECTIVES: An affordable and scalable screening model is critical for undetected glaucoma. The study evaluated the performance of an offline, smartphone-based AI system for the detection of referable glaucoma against two benchmarks: specialist diagnosis following full glaucoma workup and consensus image grading. SUBJECTS/METHODS: This prospective study (tertiary glaucoma centre, India) included 243 subjects with varying severity of glaucoma and control group without glaucoma. Disc-centred images were captured using a validated smartphone-based fundus camera analysed by the AI system and graded by specialists. Diagnostic ability of the AI in detecting referable Glaucoma (Confirmed glaucoma) and no referable Glaucoma (Suspects and No glaucoma) when compared to a final diagnosis (comprehensive glaucoma workup) and majority grading (image grading) by Glaucoma specialists (pre-defined criteria) were evaluated. RESULTS: The AI system demonstrated a sensitivity and specificity of 93.7% (95% CI: 87.6-96.9%) and 85.6% (95% CI:78.6-90.6%), respectively, in the detection of referable glaucoma when compared against final diagnosis following full glaucoma workup. True negative rate in definite non-glaucoma cases was 94.7% (95% CI: 87.2-97.9%). Amongst the false negatives were 4 early and 3 moderate glaucoma. When the same set of images provided to the AI was also provided to the specialists for image grading, specialists detected 60% (67/111) of true glaucoma cases versus a detection rate of 94% (104/111) by the AI. CONCLUSION: The AI tool showed robust performance when compared against a stringent benchmark. It had modest over-referral of normal subjects despite being challenged with fundus images alone. The next step involves a population-level assessment.

The Importance of Signal Strength Index in Optical Coherence Tomography Angiography: A Study of Eyes with Pseudoexfoliation Syndrome.

Purpose: To evaluate the effect of the signal strength index (SSI) on a comparison of the vascular and structural OCT measurements between eyes with pseudoexfoliation syndrome (PXF) and healthy controls of Asian-Indian origin. Methods: In this cross-sectional study, 33 eyes of 33 PXF patients and 40 healthy eyes of 40 controls underwent OCT and OCT angiography (OCTA). Eyes with intraocular pressure (IOP) >21mmHg, glaucomatous disc changes, or any other ocular pathology were excluded. Peripapillary vessel density (VD) and retinal nerve fiber layer (RNFL) thickness were determined from the optic disc scans. Parafoveal VD and ganglion cell complex (GCC) thickness were measured from the macular scans. These parameters were compared between the groups using mixed effect models after adjusting for clinical confounders such as IOP, as well as SSI of the scans. Results: The 2 groups were demographically similar. Average RNFL (94µm vs 100µm, p = 0.01) and GCC (91µm vs 95µm, p = 0.03) were thinner in the PXF group compared to controls. The average peripapillary VD appeared lower in the PXF groups compared to controls (58.2% vs 58.8%, p = 0.04), but after adjusting for IOP and SSI, no difference was noted (p = 0.39). After accounting for confounders, parafoveal VD in the PXF group was significantly lower compared to controls (44.3% vs 46.8%, p = 0.008). Conclusion: Peripapillary RNFL thickness, parafoveal GCC thickness and parafoveal VD were decreased in eyes with PXF when compared to controls. VD measurements are associated with the SSI and, therefore, clinicians and researchers evaluating OCTA scans quantitatively must consider the SSI value during analysis and interpretation.

Referenced scans improve the repeatability of optical coherence tomography angiography measurements in normal and glaucoma eyes.

AIM: To compare the repeatability of peripapillary perfusion density and flux index measurements on referenced and non-referenced optical microangiography (OMAG) scans in normal, glaucoma suspect and glaucoma eyes. METHODS: In a cross-sectional study, 48 eyes (33 subjects) underwent three repeat, non-referenced peripapillary OMAG scans in the same session and 43 eyes (25 subjects) underwent three referenced peripapillary OMAG scans. In the referenced scan group, repeat scans (second and the third scan) were acquired exactly on the baseline (first) scan using the 'track to prior scan' option on the device. Repeatability estimates of the mean and four-sector (temporal, superior, nasal and inferior) OMAG measurements on the non-referenced and referenced scans were assessed using within-subject coefficient of repeatability (CRw) and variation (CVw). RESULTS: CRw (%) of peripapillary perfusion density measurements (range: 2.0-4.1) on non-referenced scans were significantly higher than that on referenced scans (range: 1.4-2.7). CVw (%) on non-referenced and referenced scans ranged from 1.7 to 3.1 and from 1.2 to 2.1, respectively . CRw of flux index on non-referenced and referenced scans ranged from 4.4 to 5.8 and from 3.6 to 4.8, respectively. CVw on non-referenced and referenced scans ranged from 4.1 to 5.2 and from 3.3 to 4.5, respectively. CONCLUSIONS: Repeatability estimates of OMAG measurements were better on referenced scans compared with non-referenced scans. Perfusion density measurements had lower variability than flux index. OCTA-measured perfusion density of referenced scans is preferable for monitoring vascular change in glaucoma.

A comparison of the corneal biomechanics in pseudoexfoliation glaucoma, primary open-angle glaucoma and healthy controls using Corvis ST.

PURPOSE: To compare the corneal biomechanical parameters between pseudoexfoliation glaucoma (PXG), primary open-angle glaucoma (POAG) and healthy controls using Corvis ST. METHODS: A prospective, cross-sectional study was conducted which included 132 treatment-naïve eyes which underwent Corvis ST. The study cohort comprised of 44 eyes with PXG, 42 eyes with POAG and 46 healthy controls. Corneal biomechanical parameters, which included corneal velocities, length of corneal applanated surface, deformation amplitude (DA), peak distance and radius of curvature, were compared between the groups using analysis of variance models. RESULTS: The 3 groups were demographically similar. The mean IOP was 15.7 ±3 mmHg in the control group, 21.3 ±5 mmHg in the POAG group and 25.8 ±7 mmHg in the PXG group (p<0.0001). Corneal pachymetry was similar across the 3 groups. Mean DA was significantly lower (p<0.0001) in the PXG group (0.86 ±0.18 mm) compared to the POAG group (0.97 ±0.14mm) and the control group (1.10 ±0.15mm). Corneal velocities were also found to be statistically significantly different between the groups. However, after adjusting for IOP, there was no difference in any of the biomechanical parameters between the 3 groups. CONCLUSION: Corneal biomechanical parameters measured on Corvis ST are not different between eyes with PXG, POAG and healthy controls after adjusting for IOP.

Repeatability and comparability of peripapillary vessel density measurements of high-density and non-high-density optical coherence tomography angiography scans in normal and glaucoma eyes.

AIMS: To compare the peripapillary vessel density (VD) measurements of high-density (HD) and non-HD optical coherence tomography angiography (OCTA) scans in normal and glaucoma eyes, and to evaluate the intrasession repeatability of VD measurements of HD scans. METHODS: In a cross-sectional study, 46 normal (33 subjects) and 89 glaucoma (64 patients) eyes underwent 3 HD and 1 non-HD optic nerve head OCTA scans in the same session. Agreement in VD measurements between HD and non-HD scans was assessed using Bland and Altman analysis. Repeatability of the VD measurements of HD scans was assessed using within-subject coefficient of repeatability (CRw) and variation (CVw). RESULTS: The mean difference in the VDs ranged between 0.7% (temporal sector VD) and 2.0% (inferonasal sector VD), with HD scans showing significantly greater VD values than non-HD scans. The 95% limits of agreement (LoA) in glaucoma eyes ranged between -2.0% and 5.0% for whole enface VD and between -4.8% and 9.6% for superotemporal VD. CRw (%) and CVw (%) of VD measurements of HD scans ranged from 3.0 to 4.9 and from 2.0 to 3.1 in normal eyes. The same ranged from 3.2 to 6.7 and from 2.6 to 4.8, respectively, in glaucoma eyes. CONCLUSIONS: VD of HD scans was higher than that of non-HD scans. The wide 95% LoA indicates that the VD measurements of HD and non-HD scans cannot be used interchangeably. Test-retest repeatability of VDs on HD scans was as high as 6%. These results should be considered while using OCTA for longitudinal evaluation of glaucoma.

Surgical management of glaucoma secondary to idiopathic elevated episcleral venous pressure.

Idiopathic elevated episcleral venous pressure is characterized by dilated episcleral veins and open angle glaucoma. Trabeculectomies in these eyes are often complicated by uveal effusions (intraoperative or postoperative) at nonhypotonous pressures. We highlight the ability to avoid the need for sclerostomies by preventing intraoperative shallowing of the anterior chamber and the use of tight scleral sutures which should be adjusted postsurgery to gradually reach the target intraocular pressure in a step-wise manner.

Prostaglandin agonist effect on matrix metalloproteinase aqueous levels in glaucoma patients.

OBJECTIVE: To determine whether the aqueous levels of matrix metalloproteinases (MMPs) differ between patients with glaucoma treated with topical prostaglandin analogues and normal, nonglaucomatous control patients. Also, to note any difference in MMP levels between latanoprost, travoprost, and bimatoprost that might suggest a difference in efficacy or mechanism of action between these drugs. DESIGN: Prospective, observational study. PARTICIPANTS: Patients who were scheduled to undergo routine intraocular surgery (phacoemulsification or combined phacotrabeculectomy) as part of their standard clinical care were included. Eighteen eyes of 18 patients with glaucoma using any 1 prostaglandin analogue (latanoprost, travoprost, or bimatoprost) were compared with 8 normal control patients. METHODS: This was a multicentre study. Aqueous humour (0.2 mL) was aspirated at the beginning of the intraocular surgery through a clear corneal paracentesis. MMP-2 and -9 were quantified in the aqueous of all participants using enzyme-linked immunosorbent assay. RESULTS: There was no significant difference in the levels of either MMP-2 (p = 0.216) or MMP-9 (p = 0.552) between the control patients and the patients with glaucoma on prostaglandins. There was no difference in the levels of MMP-2 or -9 between the latanoprost, travoprost, or bimatoprost groups. CONCLUSIONS: The levels of MMP-2 and -9 in aqueous of glaucomatous eyes on topical prostaglandin analogues were the same as those of normal age-matched control patients. This could reflect either a return to normal levels with efficacious treatment or a lack of difference between disease and nondisease states.

Rigid gas-permeable contact lenses for visual rehabilitation of traumatized eyes in children.

PURPOSE: The aim of this study was to investigate the usefulness and tolerance of rigid gas-permeable (RGP) contact lenses in the visual rehabilitation of children postocular trauma. METHODS: In this retrospective case series, children below 15 years of age with ocular trauma were included. The best-corrected visual acuity with RGP contact lenses was compared with that of spectacle correction. The factors affecting visual improvement were analyzed, and problems caused by contact lens use were identified. RESULTS: Twelve eyes of 12 boys were included. The mean best-corrected visual acuity was 0.81 ± 0.29 (LogMar equivalent) with spectacles and 0.47 ± 0.27 (LogMar equivalent) with contact lenses (P < 0.001). Seven of the 12 eyes achieved a >2 line increase in visual acuity with contact lens correction as compared with that using spectacle correction. The mean astigmatism in eyes that achieved this improvement in vision was 5.45 ± 1.6 diopters, whereas the mean astigmatism in the eyes that did not improve was 2.6 ± 1.2 diopters, which was statistically significant (P = 0.009). No other factors (age, corneal scar location/density, grade/zone of injury, lens status, and occlusion) seemed to affect visual improvement with contact lenses. The mean follow-up duration was about 15 months during which 91% of the patients continued their contact lens usage. CONCLUSIONS: RGP contact lenses offer a useful refractive treatment alternative in traumatized eyes of children. Eyes with high degrees of astigmatism were found to benefit the most. RGP contact lenses were found to be well tolerated in this population.

Infectious scleritis: clinical spectrum and management outcomes in India.

In this retrospective case series, we studied the predisposing factors, causative organisms, clinical spectrum, and outcomes of 12 cases of culture-proven infectious scleritis. Nine of 12 patients had a history of preceding trauma (surgical or accidental). Past surgical history included small-incision cataract surgery (4), pterygium surgery (1), and trabeculectomy (1). Six patients had multifocal scleral abscesses due to Pseudomonas, Klebsiella, or Nocardia. Only 2 patients retained useful vision (>6/18). A poor visual acuity at presentation usually resulted in a worse visual outcome (P = 0.005). Four eyes developed phthisis. The addition of surgical intervention did not result in a significantly better visual outcome than medical management alone (P = 0.209), but resulted in a higher globe preservation rate (P = 0.045). Therefore, we concluded that infection must be ruled out in cases of scleritis with preceding history of trauma, and aggressive surgical intervention improves the anatomical outcome but does not change the visual outcome.