Contrast Discrimination and Global Form Perception in Primary Open-Angle Glaucoma and Primary Angle-Closure Glaucoma.

Purpose: This study explored early (contrast discrimination) and intermediate (global form perception) visual processing in primary subtypes of glaucoma: primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG). We aimed to understand early and intermediate visual processing in POAG and PACG, matched for similar visual field defect severity. Methods: Early visual processing was measured using a contrast discrimination task described by Porkorny and Smith (1997), and intermediate processing using a global form perception task using glass pattern coherence thresholds. Thresholds were determined centrally and at a single midperipheral location (12.5°) in a quadrant without visual field defects. Controls were tested in corresponding quadrants to individuals with glaucoma. Results: Sixty participants (20 POAG, 20 PACG, and 20 age-matched controls), aged 50 to 77 years, were included. Visual field defects were matched between POAG and PACG, with mean deviation values of -6.53 ± 4.46 (range: -1.5 to -16.85) dB and -6.2 ± 4.24 (range: -1.37 to -16.42) dB, respectively. Two-Way ANOVA revealed significant differences in thresholds between the glaucoma groups and the control group for both contrast discrimination and global form perception tasks, with higher thresholds in the glaucoma groups. Post hoc analyses showed no significant contrast discrimination difference between POAG and PACG, but POAG had significantly higher thresholds than PACG for form perception. Conclusions: In form perception, POAG showed slightly worse performance than PACG, suggesting that individuals with POAG may experience more severe functional damage than PACG of similar visual field severity.

Does the sampling frequency of an eye tracker affect the detection of glaucomatous visual field loss?

PURPOSE: Evidence suggests that eye movements have potential as a tool for detecting glaucomatous visual field defects. This study evaluated the influence of sampling frequency on eye movement parameters in detecting glaucomatous visual field defects during a free-viewing task. METHODS: We investigated eye movements in two sets of experiments: (a) young adults with and without simulated visual field defects and (b) glaucoma patients and age-matched controls. In Experiment 1, we recruited 30 healthy volunteers. Among these, 10 performed the task with a gaze-contingent superior arcuate (SARC) scotoma, 10 performed the task with a gaze-contingent biarcuate (BARC) scotoma and 10 performed the task without a simulated scotoma (NoSim). The experimental task involved participants freely exploring 100 images, each for 4 s. Eye movements were recorded using the LiveTrack Lightning eye-tracker (500 Hz). In Experiment 2, we recruited 20 glaucoma patients and 16 age-matched controls. All participants underwent similar experimental tasks as in Experiment 1, except only 37 images were shown for exploration. To analyse the effect of sampling frequency, data were downsampled to 250, 120 and 60 Hz. Eye movement parameters, such as the number of fixations, fixation duration, saccadic amplitude and bivariate contour ellipse area (BCEA), were computed across various sampling frequencies. RESULTS: Two-way ANOVA revealed no significant effects of sampling frequency on fixation duration (simulation, p = 0.37; glaucoma patients, p = 0.95) and BCEA (simulation, p = 0.84; glaucoma patients: p = 0.91). BCEA showed good distinguishability in differentiating groups across different sampling frequencies, whereas fixation duration failed to distinguish between glaucoma patients and controls. Number of fixations and saccade amplitude showed variations with sampling frequency in both simulations and glaucoma patients. CONCLUSION: In both simulations and glaucoma patients, BCEA consistently differentiated them from controls across various sampling frequencies.

Performance of home-based self-tonometry (iCare HOME (TA022)) for measuring intraocular pressure among healthy and glaucoma patients.

Introduction: The purpose of this study was to compare iCare HOME (TA022) with Goldmann applanation tonometer and to evaluate the self-tonometry measurements among the Indian population. Methods: Eligible patients underwent iCare HOME training through guided demonstration (verbal, pictorial, video) and practised self-tonometry measures using iCare HOME. Certification for independent iCare HOME measure was provided if first iCare HOME intraocular pressure (IOP) measurement fell within ± 5 mmHg of Goldmann applanation tonometer (GAT) measurement which was measured by the trained clinician (principal investigator). Certified participants underwent simulated home self-tonometry measurements using iCare HOME, and agreement with GAT IOP measurements was assessed. Results: Seven of 83 participants (8.43%) failed to complete the study due to difficulty in performing the task, leading to non-certification. Patients who could use the iCare HOME had a mean age of 53 ± 15.55years (53% males; 46% females). Only one in 12 subjects did not qualify to use iCare HOME. The overall mean difference between iCare HOME and GAT was 0.83 mmHg (95%, 3.92 and -2.25). At various pressure ranges, 7-16 mmHg, 17-23 mmHg and >23 mmHg, the mean difference between iCare HOME and GAT was 1.22 mmHg (95%, 4.32 and -1.86), 0.77 mmHg (95%,3.69 and -2.19), -0.11 mmHg (95%, 2.52 and -2.74) respectively. The intra-class correlation coefficient of the iCare HOME device was 0.997(95% CI,0.995-0.998). Conclusions: Patients were able to perform self- tonometry using iCare HOME with good reliability and safety. iCare HOME can be used to address the issue of difficulty in acquiring frequent and diurnal IOP measurements by patients doing self-tonometry from home.

A Novel Approach to Measuring Binocular Visual Fields in Glaucoma.

PRECIS: Combined average visual field index (VFI) is a simple, novel tool for binocular visual field which agrees with the existing binocular integrated visual field (IVF) model, as well as patient reported activity limitation in glaucoma. PURPOSE: The aim was to determine the correlation between novel models of binocular visual field with the existing IVF and glaucoma activity limitation (GAL-9). MATERIALS AND METHODS: IVFs were calculated from the monocular visual fields of 58 patients with primary glaucoma and the novel binocular visual field models termed binocular summation visual field index (BiSumVFI) and combined average visual field index (CaVFI) were derived from the VFIs of both fields. GAL-9 questionnaire was administered to the patients. The relationship between IVF and the 2 newer models of binocular fields were determined and the correlation of IVF, BiSumVFI, and CaVFI with GAL-9 was estimated. RESULTS: A very strong correlation was seen between IVF and BiSumVFI (r=-0.913, P<0.001, confidence interval: -0.958 to -0.821) and also between IVF and CaVFI (r=-0.896, P<0.001, confidence interval: -0.947 to -0.802). Linear regression analysis showed a significant R2 of 0.902 (P<0.001) to predict IVF from BiSumVFI and R2 of 0.847 (P<0.001) to predict IVF from CaVFI. IVF, BiSumVFI, and CaVFI correlated moderately and significantly with GAL-9 with correlation coefficients of 0.481, -0.499, and -0.505, respectively. CONCLUSION: The binocular summation VFI and combined average VFI models of binocular visual field are good predictors of IVF in glaucoma. They correlate well with the existing IVF model in estimating patients' perception of activity limitation in glaucoma.

Choroidal metastases as the presenting feature of adenocarcinoma of the lung: A case report and an overview of the role of radiotherapy in its management.

Although metastasis to the eye is the most common ophthalmic malignancy, it is usually asymptomatic and rarely a presenting symptom that leads to the diagnosis of a primary. Here, we report a patient who was evaluated for visual symptoms and was eventually diagnosed to have disseminated adenocarcinoma of the lung. He was treated with external radiotherapy to the choroidal metastasis, attaining an excellent response that was sustained until his death. A brief review on the role of radiotherapy in the management of uveal metastases is also presented.

Glaucoma and its association with obstructive sleep apnea: A narrative review.

Obstructive sleep apnea (OSA) is one of the systemic risk factors for glaucoma which causes irreversible visual field (VF) damage. We reviewed the published data of all types of studies on the association between these two conditions and papers regarding functional and structural changes related to glaucomatous damage using Scopus, web of science, and PubMed databases. There is evidence that the prevalence of glaucoma is higher in OSA patients, which independent of intraocular pressure (IOP). Studies have reported thinning of retinal nerve fiber layer (RNFL), alteration of optic nerve head, choroidal and macular thickness, and reduced VF sensitivity in patients of OSA with no history glaucoma. A negative correlation of apnea-hypopnea index with RNFL and VF indices has been described in some studies. Raised IOP was noted which is possibly related to obesity, supine position during sleep, and raised intracranial pressure. Diurnal fluctuations of IOP show more variations in OSA patients before and after continuous positive airway pressure (CPAP) therapy when compared with the normal cases. The vascular factors behind the pathogenesis include recurrent hypoxia with increased vascular resistance, oxidative stress damage to the optic nerve. In conclusion, comprehensive glaucoma evaluation should be recommended in patients with OSA and should also periodically monitor IOP during CPAP treatment which may trigger the progression of glaucomatous damage.

Subcutaneous dirofilariasis of the eyelid in a 7-month-old infant.

Human dirofilariasis is an unusual zoonotic infection (transmitted from animals to humans) presenting as a subcutaneous nodule. Occasionally it involves the eye. The parasite is transmitted to humans by mosquitoes. Presentation in infants is extremely rare. A rare case of subcutaneous dirofilariasis of the eyelid in a 7-month-old infant is reported.

Necrotizing scleritis following laser therapy for corneal vascularization.

A 68-year-old lady presented with irritation in left eye of one-week duration. Examination of her left eye revealed loose corneoscleral sutures with corneal vascularization and white deposit in the cornea in front of the blood vessels. She underwent laser photocoagulation but later developed necrotizing scleritis. We report a rare complication of necrotizing scleritis following laser photocoagulation of the corneal new vessels.

Visual loss following dacryocystectomy.

Dacryocystectomy is the surgery of choice for elderly patients with chronic dacryocystitis with a fibrotic sac. Although a simple procedure, it can cause serious complications (however rare) such as visual impairment. A 65-year-old woman who underwent bilateral dacryocystectomy is described. On the first postoperative day, she complained of pain in her left eye. Her visual acuity was light perception in the left eye. Computed tomography scan of the orbit revealed a retrobulbar hematoma on the left eye. The hematoma was drained, but the patient did not regain vision. A rare complication of visual loss following dacryocystectomy is described.