Effect of age, sex, stimulus intensity, and eccentricity on saccadic reaction time in eye movement perimetry

Purpose: In eye movement perimetry (EMP), the extent of the visual field is tested by assessing the saccades using an eye tracker. The aim of the present study was to determine the effects of age and sex of the subjects, the eccentricity and intensity of the peripheral stimuli on saccadic reaction time (SRT), and the interaction between these parameters in healthy participants. Methods: Healthy participants aged between 20 to 70 years underwent a complete ophthalmic examination and an EMP test. SRT was determined from detected peripheral stimuli of four intensity levels. A multilevel mixed-model analysis was used to verify the influence of subject and stimulus characteristics on SRT within the tested visual field. Results: Ninety-five subjects (mean age 43.0 [15.0] years) were included. Age, stimulus intensity, and eccentricity had a statistically significant effect on SRT, not sex. SRTs were significantly faster with increasing stimulus intensity and decreasing eccentricity (P < 0.001). At the lowest stimulus intensity of 192 cd/m2, a significant interaction was found between age and eccentricity. Conclusions: The current study demonstrated significant SRT dependence across the visual field measured up to 278, irrespective of sex. The presented SRT values may serve as a first normative guide for EMP. Translational Relevance: This report of SRT interaction can aid in refining its use as a measure of visual field responsiveness

Assessment of macular visual functions in patients with risk for obstructive sleep apnea syndrome

Purpose: To study and compare the macular visual functions among the subjects with and without risk for Obstructive Sleep Apnea Syndrome. Methods: Prospective case–control study involving 20 cases and 17 controls. Subjects were classified as cases with the presence of snoring and controls in the absence of it. Cases were administered with a standardized Berlin Questionnaire and were grouped as high risk and low risk based on their scores. Color discrimination, contrast sensitivity, and photo stress recovery test were measured following a comprehensive eye examination. Body mass index and neck circumference were also measured. Results: There were 13 subjects in the high-risk category, 7 subjects in the low-risk category, and 17 subjects in the control group. The total error score in color discrimination was significantly different among high risk (112 ± 84.17), low risk (74 ± 43.98), and controls (56 ± 39.43) (P = 0.04) whereas, contrast sensitivity (P = 0.897), visual acuity (P = 0.95), and photo stress recovery test (P = 0.32) did not show any significant difference. Conclusion: High-risk category subjects showed poor color discrimination than controls hence, these individuals must undergo a detailed ophthalmic examination with a color discrimination test and must be evaluated in a sleep clinic

Multifocal versus modified monovision corrections: A non-dispensing comparison of visual assessment in presbyopic neophytes

Purpose: To compare the visual performance of two simultaneous-vision soft multifocal contact lenses and to compare multifocal contact lens and its modified monovision counterpart in presbyopic neophytes.Methods: A double-masked, prospective, comparative study was conducted on 19 participants fitted with soft PureVision2 multifocal (PVMF) and clariti multifocal (CMF) lenses in random order. High- and low-contrast distance visual acuity, near visual acuity, stereopsis, contrast sensitivity, and glare acuity were measured. The measurements were conducted using multifocal and modified monovision design with one brand and then repeated with another brand of lens. Results: High-contrast distance visual acuity showed a significant difference between CMF (0.00 [−0.10–0.04]) and PureVision2 modified monovision (PVMMV; −0.10 [−0.14–0.00]) correction (P = 0.003) and also between CMF and clariti modified monovision (CMMV; −0.10 [−0.20–0.00]) correction (P = 0.002). Both modified monovision lenses outperformed CMF. The current study did not show any statistically significant difference between contact lens corrections for low-contrast visual acuity, near visual acuity, and contrast sensitivity (P > 0.01). Stereopsis at near distance was significantly lower with both modified monovision (PVMMV: 70 [50–85]; P = 0.007, CMMV: 70 [70–100]; P = 0.006) and with CMF (50 [40–70]; P = 0.005) when compared to spectacles (50 [30–70]). Glare acuity was significantly lower with multifocal (PVMF: 0.46 [0.40–0.50]; P = 0.001, CMF: 0.40 [0.40–0.46]; P = 0.007) compared with spectacles (0.40 [0.30–0.40]), but no significant difference was noted between the multifocal contact lenses (P = 0.033). Conclusion: Modified monovision provided superior high-contrast vision compared to multifocal correction. Multifocal corrections performed better for stereopsis when compared to modified monovision. In parameters like low-contrast visual acuity, near acuity, and contrast sensitivity, both the corrections performed similarly. Both multifocal designs showed comparable visual performances

Prevalence and causes of low vision and blindness in an urban population: The Chennai Glaucoma Study

Aim: To evaluate the prevalence and causes of low vision and blindness in an urban south Indian population. Settings and Design: Population-based cross-sectional study. Exactly 3850 subjects aged 40 years and above from Chennai city were examined at a dedicated facility in the base hospital. Materials and Methods: All subjects had a complete ophthalmic examination that included best-corrected visual acuity. Low vision and blindness were defined using World Health Organization (WHO) criteria. The influence of age, gender, literacy, and occupation was assessed using multiple logistic regression. Statistical Analysis: Chi-square test, t-test, and multivariate analysis were used. Results: Of the 4800 enumerated subjects, 3850 subjects (1710 males, 2140 females) were examined (response rate, 80.2%). The prevalence of blindness was 0.85% (95% CI 0.6-1.1%) and was positively associated with age and illiteracy. Cataract was the leading cause (57.6%) and glaucoma was the second cause (16.7%) for blindness. The prevalence of low vision was 2.9% (95% CI 2.4-3.4%) and visual impairment (blindness + low vision) was 3.8% (95% CI 3.2-4.4%). The primary causes for low vision were refractive errors (68%) and cataract (22%). Conclusions: In this urban population based study, cataract was the leading cause for blindness and refractive error was the main reason for low vision

Long-term change in central corneal thickness from a glaucoma perspective

Aim: To investigate the longitudinal change in central corneal thickness (CCT) over 3 years in patients with glaucoma. Materials and Methods: The Chennai Glaucoma Follow-up Study, an offshoot of the Chennai Glaucoma Study, was designed to evaluate the progression of glaucoma. A cohort of participants in the Chennai Glaucoma Study that were suffering from glaucoma or were at a higher risk for glaucoma underwent comprehensive ophthalmic evaluation at the base hospital at 6-month intervals during the years 2004 to 2007. The CCT (average of 10 readings) was measured between 11 am and 1 pm on any given day using an ultrasonic pachymeter. Patients with a history of ocular surgery, corneal disease and usage of topical carbonic anhydrase inhibitor were excluded. No patient was a contact lens wearer. Results: One hundred and ninety-six patients (84 male, 112 female) met the inclusion criteria. We analyzed data from the right eye. The mean age of the patients was 59.97 ± 9.06 years. Fifty-nine (30.1%) of the patients were diabetic. The mean change in CCT (CCT at first patient visit - CCT at last patient visit) was 3.46 ± 7.63 μm. The mean change in CCT was 0.75 μm per year (R 2 = 0.00). Age, gender, intraocular pressure at the first patient visit and diabetic status had no significant influence on the magnitude of change in CCT. Conclusion: A carefully obtained CCT reading by a trained examiner need not be repeated for at least 3 years as long as the ocular and systemic factors known to affect the measurement of CCT are constant

Comparison of saccadic reaction time between normal and glaucoma using an eye movement perimeter

Aim: To compare the saccadic reaction time (SRT) in both the central and peripheral visual field in normal and glaucomatous eyes using eye movement perimetery (EMP). Materials and Methods: Fifty-four normal and 25 glaucoma subjects underwent EMP and visual field testing on the Humphrey Field Analyser (HFA) 24-2 program. The EMP is based on infrared tracking of the corneal reflex. Fifty-four test locations corresponding to the locations on the 24-2 HFA program were tested. SRTs at different eccentricities and for different severities of glaucoma were compared between normal and glaucoma subjects. Results: Mean SRT was calculated for both normal and glaucoma subjects. Mann-Whitney U test showed statistically significant (P < 0.001) differences in SRT′s between normal and glaucoma subjects in all zones. Conclusion: SRT was prolonged in eyes with glaucoma across different eccentricities

Genetic Association of SNPs near <i>ATOH7</i>, <i>CARD10</i>, <i>CDKN2B</i>, <i>CDC7</i> and <i>SIX1/SIX6</i> with the Endophenotypes of Primary Open Angle Glaucoma in Indian Population

<div><p>Primary open angle glaucoma (POAG) belonging to a group of optic neuropathies, result from interaction between genetic and environmental factors. Study of associations with quantitative traits (QTs) is one of the successful strategies to understand the complex genetics of POAG. The current study attempts to explore the association of variations near/in genes like <i>ATOH7</i>, <i>SIX1/SIX6</i> complex, <i>CDKN2B</i>, <i>CARD10</i>, and <i>CDC7</i> with POAG and its QTs including vertical cup to disc ratio (VCDR), central corneal thickness (CCT), intra ocular pressure (IOP), and axial length (AL). Case-control study design was carried out in a sample size of 97 POAG cases and 371 controls from South India. Model-based (additive, recessive, dominant) association of the genotypes and their interaction was carried out between cases and controls using chi-square, linear and logistic regression methods. Nominal significance (<i>P</i><0.05) was observed for QTs like i) VCDR with SNPs rs1900004 (<i>ATOH7</i>); rs1192415 (<i>CDC7)</i>; rs10483727 (<i>SIX1/SIX6)</i>, rs9607469 (<i>CARD10);</i> ii) CCT with rs1192415; iii) IOP with rs1900004 and iv) AL with rs1900004 and rs1063192 (<i>CDKN2B)</i>. We were able to replicate previously known interactions between <i>ATOH7-SIX6</i> and <i>SIX6-CDKN2B</i> along with few novel interactions between <i>ATOH7</i>—<i>CDC7</i> and <i>SIX6</i> with genes including <i>CARD10</i> and <i>CDC7</i>. In summary, our results suggest that a probable interaction among the candidate genes for QTs, play a major role in determining the individual’s susceptibility to POAG.</p></div

Development of a test grid using Eye Movement Perimetry for screening glaucomatous visual field defects

Background: Eye Movement Perimetry (EMP) uses Saccadic Eye Movement (SEM) responses for visual field evaluation. Previous studies have demonstrated significant delay in initiation of SEMs among glaucoma patients in comparison with healthy subjects. The aim of the current study was to develop an EMP-based screening grid to identify glaucomatous visual field defects. Methods: An interactive test consisting of 36 locations and two stimulus contrasts (162 cd/m2 and 190 cd/m2 on a background of 140 cd/m2) was evaluated in 54 healthy subjects and 50 primary glaucoma patients. Each subject was presented a central fixation target combined with the random projection of Goldmann size III peripheral targets. Instructions were given to look at each peripheral target on detection and then re-fixate at the central fixation target while the saccades were assessed using an eye tracker. From each seen peripheral target, the Saccadic Reaction Time (SRT) was calculated for contrast level 162 cd/ m2. These values were used to plot Receiver Operating Characteristic (ROC) curves for each test locations and the Area Under the Curve (AUC) values were used to identify the locations with highest susceptibility to glaucomatous damage. Each stimulus location with an AUC less than 0.75 along with its mirrored test location around the horizontal axis were eliminated from the grid. Results: The mean age was 48.1 ± 16.6 years and 50.0 ± 14.5 years for healthy subjects and glaucoma patients respectively. A significant increase of SRT values by 76.5% (p < 0.001) was found in glaucoma patients in comparison with the healthy subjects. From the ROC analysis, ten out of 36 locations meeting the cut-off criteria of AUC were eliminated resulting in a new grid containing 26 test locations. SRT values were significantly different (p < 0.05) between the healthy subjects and glaucoma irrespective of the grids used. Conclusions: The present study resulted in a screening grid consisting of 26 locations predominantly testing nasal, superior and inferior areas of the visual field. An internal validation of the modified grid showed 90.4% of screening accuracy which makes it a potential approach for population based glaucoma screening

Demographic and clinical features of the study subjects.

<p>*the age at recruitment for controls or age of disease onset for POAG patients are shown</p><p>SD-standard deviation, IOP- intraocular pressure, VCDR-vertical cup to disc ratio, CCT- central corneal thickness, AL- axial length, ACD- anterior chamber depth.</p><p>Demographic and clinical features of the study subjects.</p