A modified analysis protocol for the PhNR test.

PURPOSE: Several studies have reported that glaucoma patients have abnormal photopic negative response (PhNR) results compared to reference control subjects. The International Society for Clinical Electrophysiology of Vision (ISCEV) released an extended protocol for PhNR (I-PhNR) in 2018. The purpose of this study was to compare the I-PhNR protocol to a similar protocol modified (M-PhNR) to enhance the performance of the method in detecting glaucomatous damage. METHODS: Thirty subjects were enrolled in this study (12 glaucoma patients, 10 glaucoma suspects, 8 normal controls). PhNR tests were conducted with a Diagnosys E3 mobile system (Diagnosys LLC, Lowell, MA). I-PhNR tests utilized all parameters specified by the ISCEV requirement. M-PhNR tests used the same parameters as the ISCEV tests with the exceptions of a 5-45 Hz bandpass filter and a novel, objective sweep-selection parameter. According to the ISCEV protocol, the PhNR relative to baseline (i.e., BT), a-wave and b-wave response amplitudes and BT/b-wave amplitude ratios were measured. Coefficients of variation, receiver operating characteristic (ROC) curves, and t-tests were used to assess the data from one randomly chosen eye per subject. RESULTS: The M-PhNR protocol resulted in a decrease in the intra-subject repeat test coefficient of variation and a decrease in the average inter-subject coefficient of variation for the glaucoma subjects. The ROC curves demonstrated an increase in the area under the curve (AUC) for the M-PhNR compared to the I-PhNR protocol. The sensitivity and specificity were also greater for the M-PhNR protocol. CONCLUSIONS: The M-PhNR protocol resulted in a decrease in intra-subject and inter-subject data variability which resulted in a significant increase in the ROC AUC, sensitivity, and specificity for glaucoma. Thus, the M-PhNR protocol shows promise as a better diagnostic tool than the I-PhNR protocol for detecting glaucoma.

Long-term follow-up of torpedo maculopathy: a case series and mini-review.

BACKGROUND: Torpedo maculopathy (TM) is a rare, congenital condition characterized by an oval-shaped, chorioretinal lesion in the temporal macula of unknown etiology. To our knowledge, the longest reported follow-up of TM is 5 years. Herein we report 10 years of follow-up on two patients with TM to further characterize the long-term natural history of the condition. CASE REPORTS: Two patients with torpedo maculopathy were examined at baseline and then again at 5 years and 10 years from baseline. Eyes were evaluated using color fundus photography, automated perimetry, fundus autofluorescence and spectral domain optical coherence tomography. Visual function of both patients remained stable throughout the observation period. In case 1, there was no evidence of change in lesion morphology over the 10 year observation period. Case 2 showed progression of cystic degeneration of the neurosensory retina within the torpedo lesion. Case 1 reported a history of supernumerary teeth and underwent gene sequence with deletion/duplication analyses of the APC gene but no clinically significant variants were detected. CONCLUSIONS: Our findings support the position that TM is a nonprogressive condition with long-term stability of visual function. Genetic analysis of case 1 failed to detect any association with Gardner syndrome.

Comparison of contrast sensitivity in macaque monkeys and humans.

Contrast sensitivity functions reveal information about a subject's overall visual ability and have been investigated in several species of nonhuman primates (NHPs) with experimentally induced amblyopia and glaucoma. However, there are no published studies comparing contrast sensitivity functions across these species of normal NHPs. The purpose of this investigation was to compare contrast sensitivity across these primates to determine whether they are similar. Ten normal humans and eight normal NHPs (Macaca fascicularis) took part in this project. Previously published data from Macaca mulatta and Macaca nemestrina were also compared. Threshold was operationally defined as two misses in a row for a descending method of limits. A similar paradigm was used for the humans except that the descending method of limits was combined with a spatial, two-alternative forced choice (2-AFC) technique. The contrast sensitivity functions were fit with a double exponential function. The averaged peak contrast sensitivity, peak spatial frequency, acuity, and area under the curve for the humans were 268.9, 3.40 cpd, 27.3 cpd, and 2345.4 and for the Macaca fascicularis were 99.2, 3.93 cpd, 26.1 cpd, and 980.9. A two-sample t-test indicated that the peak contrast sensitivities (P = 0.001) and areas under the curve (P = 0.010) were significantly different. The peak spatial frequencies (P = 0.150) and the extrapolated visual acuities (P = 0.763) were not different. The contrast sensitivities for the Macaca fascicularis, Macaca mulatta, and Macaca nemestrina were qualitatively and quantitatively similar. The contrast sensitivity functions for the NHPs had lower peak contrast sensitivities and areas under the curve than the humans. Even though different methods have been used to measure contrast sensitivity in different species of NHP, the functions are similar. The contrast sensitivity differences and similarities between humans and NHPs need to be considered when using NHPs to study human disease.

A comparison of contrast sensitivity and sweep visual evoked potential (sVEP) acuity estimates in normal humans.

PURPOSE: Several previous studies have demonstrated that for normal adult subjects the optotype acuity measured with charts is better than the acuity determined with the sweep visual evoked potential (sVEP) using gratings or checks. However, there is no difference in psychophysical measures of acuity with optotype or grating charts. Thus, it is unclear whether the acuity discrepancy between optotype charts and the sVEP result from the stimulus design or other methodological differences. The purpose of this experiment is to determine the relationship between acuities extrapolated from a contrast sensitivity function (CSF) that uses optotypes and the sVEP. METHODS: Normal subjects (N = 10) with acuity of 0.00 logMAR or better (ETDRS chart) were recruited for this study. Two commercially available systems were used to measure CSFs [i.e., the Beethoven System (Ryklin Software, NY) and the qCSF system (Adaptive Sensory Tech, CA)]. The stimuli for the Beethoven were sine wave gratings (0.75-18.50 cpd), and thresholds were determined with a 2-alternative forced choice (2-AFC) procedure combined with a staircase. The stimuli for the qCSF system were spatially filtered letters (10 possible letters, 10-AFC) with the letter sizes and contrasts determined by a Bayesian adaptive procedure. Visual acuity was determined by fitting the data with a double exponential equation and extrapolating the fit to a contrast sensitivity of one. The sVEP was obtained with the PowerDiva (Digital Instrumentation for Visual Assessment, version 3.5, CA). The stimuli were sine wave gratings (80% contrast, 3-36 cpd) counterphased at 7.5 Hz. The final acuity was the average of two estimates each derived from the average of 10 sweeps. RESULTS: The average logMAR chart (acuity converted to cpd), sVEP, Beethoven, and qCSF acuities were 36.6 ± 4.62 cpd (mean ± SD), 31.2 ± 4.59 cpd, 27.3 ± 7.38 cpd, and 27.6 ± 6.36 cpd, respectively. The logMAR chart acuity was significantly different from the other acuity estimates (all p values < 0.05). The sVEP, Beethoven, and qCSF acuities were not different from one another (all p values > 0.05). The Beethoven and the qCSF acuities had a good intraclass correlation coefficient (ICC = 0.85). CONCLUSIONS: Similar to previous publications, the sVEP acuity estimate was less than the optotype chart acuity. The acuity determined with the sVEP and the CSFs with letter and grating stimuli were not statistically different, suggesting that the difference in acuity with the sVEP and optotype charts does not result from stimulus differences. Other methodological differences must account for the discrepancy in sVEP and optotype chart acuity.

Case Report: Delayed Vitamin A Retinopathy Secondary to Bariatric Surgery.

SIGNIFICANCE: Although rare, vitamin A retinopathy should be considered by the clinicians in their differentials for conditions that can lead to nyctalopia, especially in those patients who have undergone bariatric surgery. Patients must be educated on this potential delayed adverse effect of the surgery and possible lifelong vitamin A supplementation. PURPOSE: The purpose of this study was to report a rare case of delayed vitamin A retinopathy that occurred because of vitamin A malabsorption secondary to bariatric surgery. CASE REPORT: A 55-year-old woman presented with nyctalopia and dark adaptation problems. The patient had a history of gastric bypass surgery 22 years earlier. Fundus examination revealed a large number of small white dots in the midperiphery of both eyes. Electrophysiology testing revealed flat-lined scotopic responses. Vitamin A levels were found to be severely reduced. Subsequent vitamin A supplementation resulted in the reversal of all signs and symptoms. CONCLUSIONS: This case report demonstrates the importance of considering vitamin A deficiency in patients who present with symptoms of nyctalopia with a history of bariatric surgery. Clinicians should be aware of a possible delayed onset and refer for appropriate testing and treatment, as vitamin A retinopathy has been shown to be reversible. Because other conditions can present with nyctalopia and retinal white spots, clinicians also need to consider the appropriate differential diagnoses. Lifelong monitoring is indicated because reoccurrences have been reported.

Rescue of Glaucomatous Neurodegeneration by Differentially Modulating Neuronal Endoplasmic Reticulum Stress Molecules.

UNLABELLED: Axon injury is an early event in neurodegenerative diseases that often leads to retrograde neuronal cell death and progressive permanent loss of vital neuronal functions. The connection of these two obviously sequential degenerative events, however, is elusive. Deciphering the upstream signals that trigger the neurodegeneration cascades in both neuronal soma and axon would be a key step toward developing the effective neuroprotectants that are greatly needed in the clinic. We showed previously that optic nerve injury-induced neuronal endoplasmic reticulum (ER) stress plays an important role in retinal ganglion cell (RGC) death. Using two in vivo mouse models of optic neuropathies (traumatic optic nerve injury and glaucoma) and adeno-associated virus-mediated RGC-specific gene targeting, we now show that differential manipulation of unfolded protein response pathways in opposite directions-inhibition of eukaryotic translation initiation factor 2α-C/EBP homologous protein and activation of X-box binding protein 1-promotes both RGC axons and somata survival and preserves visual function. Our results indicate that axon injury-induced neuronal ER stress plays an important role in both axon degeneration and neuron soma death. Neuronal ER stress is therefore a promising therapeutic target for glaucoma and potentially other types of neurodegeneration. SIGNIFICANCE STATEMENT: Neuron soma and axon degeneration have distinct molecular mechanisms although they are clearly connected after axon injury. We previously demonstrated that axon injury induces neuronal endoplasmic reticulum (ER) stress and that manipulation of ER stress molecules synergistically promotes neuron cell body survival. Here we investigated the possibility that ER stress also plays a role in axon degeneration and whether ER stress modulation preserves neuronal function in neurodegenerative diseases. Our results suggest that neuronal ER stress is a general mechanism of degeneration for both neuronal cell body and axon, and that therapeutic targeting of ER stress produces significant functional recovery.

Effect of Povidone Iodine 5% on the Cornea, Vision, and Subjective Comfort.

PURPOSE: To determine the effects of povidone iodine 5% (Betadine 5%) applied to the eye on visual function, corneal integrity, and subjective complaints. METHODS: Ten subjects were chosen to participate in this study (average age 40.6 ± 19.6; age range 22-68). LogMAR acuity, contrast sensitivity, corneal fluorescein staining, and subjective complaints were measured before and after 60 µl of Betadine 5% or saline were applied to one eye (eligibility visit, baseline, 5, 30, and 60 minutes and 4 and 24 hours post-application). Contrast sensitivity at 14 cpd was determined with a spatial two-alternative, forced choice procedure (Beethoven software). The National Eye Institute (NEI) grid pattern was used to grade corneal staining with sodium fluorescein. To avoid the detrimental effects of sodium fluorescein administration on functional vision, the corneal staining baseline was measured at the eligibility visit. Subjective complaints were monitored using the Schein dry eye questionnaire. RESULTS: The data were analyzed with an ANOVA. Saline administration did not alter logMAR acuity, contrast sensitivity, corneal fluorescein staining, or subjective complaints at any visit. Betadine administration significantly reduced the logMAR acuity, compared to baseline and the saline data, at the 30- and 60-minute visits (all P values <.05). The contrast sensitivity was significantly reduced compared to the baseline and the saline results at 5, 30, and 60 minutes after Betadine application (all P values <.05). The Betadine significantly increased the Schein questionnaire score, compared both to baseline and the saline data, at the 1- and 4-hour visits (all P values <.05). Total corneal staining and the maximum NEI sector staining were significantly different from baseline and from the saline results at every visit (all P values <.05). CONCLUSIONS: Betadine 5% application significantly decreases epithelial integrity of the cornea, decreases functional vision, and increases subjective complaints.

Gyrate Atrophy-Like Phenotype: Normal Plasma Ornithine and Retinal Crystals.

PURPOSE: To report an unusual case of a gyrate atrophy-like presentation with retinal crystal deposition in a patient with normal plasma ornithine levels. CASE REPORT: A 50-year-old Hispanic female patient presented with complaints of blurred vision and nyctalopia. Examination revealed bilateral multiple round islands of peripheral chorioretinal degeneration in addition to small crystal-like deposits in the posterior pole. Spectral domain optical coherence tomography confirmed the crystalline deposits to be above the retinal pigment epithelium. Electrophysiology revealed reduced photopic responses with no recordable scotopic response. Testing for elevated plasma ornithine, which is typical in gyrate atrophy patients, was performed; however, the patient's levels were normal. CONCLUSIONS: Diagnosis of conditions that cause nyctalopia can be challenging because they are rare and often similar in appearance and presenting symptoms. Retinal crystal deposition and normal plasma ornithine illustrate the phenotypical variation that can be seen in a gyrate atrophy-like phenotype.

Comparing enfant and PowerDiva sweep visual evoked potential (sVEP) acuity estimates.

PURPOSE: Many studies have examined different variables that affect the outcome of sVEP estimated acuity. However, no studies have compared the estimated sVEP acuity between different instruments. The primary purpose of this study was to compare sVEP acuity estimates obtained with two different sVEP systems: the Enfant and the PowerDiva. METHODS: Twenty-five normal adults with monocular acuities of 0.10 logMAR or better took part in this study. The sVEP acuities were determined with the two instruments in a single visit with the same electrode placement. For both systems, the stimuli were horizontal sine wave gratings of 80 % contrast, counterphased at 7.5 Hz, with a screen mean luminance of 100 cd/m(2). The sweep presented spatial frequencies from 3 to 36 cpd with each spatial frequency presented for 1 s. Ten presentations of the stimuli were averaged together for one acuity measurement. The acuity estimate was made with the specific instruments standard software. Two acuity measurements were made for each system and averaged together for further comparison. The acuity estimates were compared using an ANOVA, paired t tests, and Bland-Altman plots. RESULTS: The average estimated logMAR acuities with the Enfant (0.064 ± 0.069 logMAR) and PowerDiva (0.065 ± 0.115 logMAR) were not significantly different (t = 0.04, p = 0.97). Consistent with previous studies, the logMAR chart acuity (-0.086 ± 0.089 logMAR) was significantly different from the Enfant (t = 8.10, p < 0.001) and PowerDiva (t = 5.77, p < 0.001) acuity estimates. The Bland-Altman analysis for the two instruments did not indicate a bias (-0.001), and the limit of agreement was 0.227 logMAR. CONCLUSIONS: Acuity estimates with the Enfant and PowerDiva are not significantly different for patients with normal acuity. Thus, direct comparisons between the two instruments can be made for patients with normal acuity.

Evaluation of reading speed and contrast sensitivity in dry eye disease.

PURPOSE: Visual disturbance is a common symptom reported by patients with dry eye disease (DED). The purpose of this study was to evaluate visual performance, including reading speed and contrast sensitivity, in control and DED subjects. METHODS: Fifty-two DED patients (mild, n = 17; moderate, n = 22; severe, n = 13; based on corneal staining and the Ocular Surface Disease Index ≥ 20) and 20 control subjects (Ocular Surface Disease Index <13, no corneal staining) took part in this study. The age ranges for the control and DED patients were 18 to 45 years and 19 to 84 years, respectively. Contrast sensitivity was measured using the Holladay Automated Contrast Sensitivity System, and reading speed was determined using the Wilkins Rate of Reading Test. Analysis of covariance was conducted to compare clinical characteristics among subject groups while adjusting for age, sex, and study site. Partial correlation coefficients from linear regression were used to measure the linear relationship between contrast sensitivity and reading speed with DED parameters. RESULTS: The log of the minimum angle of resolution visual acuities and contrast sensitivity were not significantly different across subject groups. The DED patients (134.9 ± 4.95 words per minute) exhibited slower reading speeds than the control subjects (158.3 ± 8.40 words per minute, p = 0.046). As DED severity increased, the reading speed decreased (141.0 ± 7.96 words per minute, 136.8 ± 7.15 words per minute, and 127.0 ± 9.63 words per minute in mild, moderate, and severe groups, respectively). Reading rate was found to correlate weakly with corneal staining based on a partial correlation coefficient (-0.345, p < 0.001) but not with other DED parameters. CONCLUSIONS: The reading rate was lower in DED subjects than that in control subjects. As the DED severity increased, the reading rate decreased. This finding is consistent with patient-reported symptoms and provides direct evidence for the impact of DED on reading performance. These findings suggest that reading speed may be used to monitor treatment benefit in DED.

Reliability of acuities determined with the sweep visual evoked potential (sVEP).

sVEPs are generally used to rapidly obtain visual acuity. Several studies have determined the reliability of acuity measurements with psychophysical techniques. The aim of this study was to determine the intersession and intrasession variabilities of sVEP measurements. Twenty-four normal, adult subjects took part in this project. Stimulus production and data analyses were done using an Enfant 4010. Standard VEP recording techniques were employed. Data were collected on two separate days (at least 1 week apart). At each visit, two complete sets of sVEP data were collected and averaged. A logMAR acuity chart was also used to determine the acuity at each visit. Paired t tests, 95% confidence intervals, intraclass correlation coefficients, and coefficients of repeatability were used to determine whether there was a difference in the intrasession and intersession acuities. The mean acuity difference and coefficient of repeatability were +0.01 and 0.191 for visit 1 and -0.019 and 0.186 for visit 2, respectively. The mean acuity difference and coefficient of repeatability across visits were +0.008 and 0.176 for the first acuity and-0.02 and 0.170 for the second acuity, respectively. Paired t tests did not find a significant difference between any set of data or the average for visits one and two (all P values > 0.05). The intraclass correlation coefficients comparing the average sVEP data and the logMAR data for visits 1 and 2 were 0.71 and 0.88, respectively. The coefficients of repeatability for the averaged sVEP acuity and the logMAR acuity for the two visits were 0.11 and 0.07, respectively. The repeatability of the sVEP acuity estimate in a large population of adults is similar to that of previous published reports on infants and is nearly as high as that of logMAR acuity chart data. The repeatability is the same for single best estimates of acuity and averaged estimates of acuity across visits.

Contrast Sensitivity in Early to Intermediate Age-Related Macular Degeneration (AMD).

PURPOSE: Previous studies indicated that advanced age-related macular degeneration (AMD) affects contrast sensitivity (CS) in humans. The CS results for early/intermediate AMD patients are contradictory. The purpose of this study was to determine if CS testing discriminates early/intermediate AMD patients with normal acuity from normal patients. METHODS: Forty-nine subjects (25 control and 24 early/intermediate AMD patients) were chosen for this project. The age (p = .16) and acuity (p = .34) was not significantly different between the groups. The average simplified AREDS AMD grade for the AMD patients was 2.75 ± 1.03. Three CS functions employing a descending method of limits were measured at the fovea (1. stationary stimulus and, 2. 16 Hz counter-phase stimulus under photopic conditions and 3. the stationary stimulus viewed through a 2 log unit neutral density filter (mesopic condition, background luminance of 1 cd/m2)) and at 4 deg right or left of the fovea with a horizontally oriented sine wave grating (5 deg diameter) viewed on a VPixx monitor (luminance of 100 cd/m2). RESULTS: The early AMD patients were no different from the control patients for any test condition. The intermediate AMD patients were significantly different from the control patients for the mesopic CS function (p = .05). Post-hoc 2-sample t-tests for the intermediate AMD patients were significantly different from the control patients under the stationary photopic and mesopic conditions for the 1.5 cycle per degree stimulus. CONCLUSIONS: Group differences in CS were only found in intermediate AMD patients. The loss in CS increased for the intermediate AMD patients under low light levels. Thus, CS may not be the optimal test to discriminate early AMD from control patients so other tests measured under dark adapted conditions should be investigated.

Visual effect and residence time of artificial tears in dry eye subjects.

PURPOSE: The purpose of this investigation was to examine the relationship between the visual effect (VE) and residence time (RT) of artificial tears (ATs) in dry eye subjects. METHODS: The VEs and RTs were measured after administration of 25 µl of an AT into the inferior fornix of 18 dry eye subjects. The VE was investigated by measuring contrast sensitivity before and after AT administration. The return to baseline sensitivity (RTBS) was taken as the time it took to return to within 1 SD of baseline contrast sensitivity. RT was measured using fluorescent formulations and a scanning fluorometer. RESULTS: No correlation was found between RTBS and RT for a low viscosity (saline-F) and a medium viscosity AT (CMC-F; p>0.05). There was a moderate correlation for a higher viscosity AT (PEG-F; p=0.03). For all solutions, RT was significantly longer than RTBS (p<0.001). There was a significant difference in RTBS between saline-F and PEG-F (p=0.002) but not between saline-F and CMC-F (p=0.87). There was a significant difference in RT between saline-F and both PEG-F and CMC-F (p<0.001 and p=0.018, respectively). CONCLUSIONS: No correlation was found between RTBS and RT for saline-F or CMC-F (moderate correlation for PEG-F). These ATs are present on the eye for a significantly longer time than their adverse affect on vision. An ideal AT would result in minimal if any initial blur on instillation while remaining in the eye for an extended period of time.

Impaired visual performance in patients with dry eye.

Patients with dry eye disease (DED) often complain about poor vision, which is not easily quantifiable. This review assesses the current understanding of clinical evaluations of visual function in patients with DED. Several noninvasive techniques for the assessment of visual performance have been utilized in patients with DED, and these are critically reviewed in relation to the visual symptoms experienced by these patients. It is clear that none of the current techniques is ideal, and there is not one appropriate, simple, clinical test that can be used for assessing visual impairment in patients with DED. Evidence from a comprehensive literature search combined with clinical experience have been used to identify which tests are currently of most benefit and to highlight the future development of a more specific clinical test for visual impairment in the dry eye patient.

Measuring near-induced transient myopia in college students with visual discomfort.

PURPOSE: Visual discomfort is a common problem, and our previous research indicated that 17% of college students experience moderate to high levels of discomfort when reading or studying. There have been several visual factors associated with visual discomfort, and in this study, we focused on measuring the near-induced transient myopia response in a group of college students with significant visual discomfort. METHODS: Visual discomfort was evaluated with a survey developed by Conlon et al. (Conlon et al., Visual Cogn 1999;6:637-663). Twelve college students with high visual discomfort (scoring 1 SD higher than the mean value) and 12 college students with low visual discomfort (scoring within 0.5 SD of the mean value) participated in the study. All students had 20/25 or better visual acuity, no strabismus, and no significant uncorrected refractive error. All refractive error and accommodative measurements were made with the WAM-5500 autorefractor. A pretask distance refraction at 6 m was taken for 60 s, and then the students read a story for 10 min at 20 cm. After reading the passage, the posttask distance refraction was measured for 2 min at 6 m. Values for the pre- and posttask measures were averaged in 10-s blocks of time. RESULTS: A mixed analysis of variance comparing discomfort group by pre- and postnear work distance refraction showed a significant interaction (p = 0.05). Comparing the means of the pre- and posttask distance refraction indicated that the high discomfort group showed no change in refractive error, but the low discomfort group showed a myopic shift of 0.13 diopter. CONCLUSIONS: A near-induced transient myopia response is not associated with high visual discomfort experienced by college students when reading or doing near work.

Visual discomfort and objective measures of static accommodation.

PURPOSE: Accommodation insufficiency and fatigue have been associated with near work visual discomfort symptoms, but clinical measures of accommodation amplitude suggest insufficiency is uncommon and often not weak enough to cause symptoms. However, recent studies show that the clinical push-up test used to measure amplitude overestimates accommodative function. This study uses an open-field autorefractor to measure accommodative stimulus-response functions objectively in college students with and without near work induced discomfort symptoms. METHODS: Using a Grand-Seiko WAM 5500 autorefractor, 2 min recordings were made each at five viewing distances (0 to 5 D) to measure an accommodative response function. Visual discomfort symptoms were assessed using the Conlon survey. RESULTS: A strong and positive correlation between accommodative lag and visual discomfort symptoms was found under near work conditions. The prevalence of accommodative insufficiency was much higher than estimated by clinical measures. CONCLUSIONS: Accommodative insufficiency and fatigue should be defined and described by objective methods using extended viewing times to assess function.

Contrast sensitivity and tear layer aberrometry in dry eye patients.

PURPOSE: Dry eye disease is a common condition that affects millions of people world wide. The common findings of dry eye disease are blurred vision and tear film instability. The purpose of this study was to determine if long-term use of artificial tears altered visual disturbances and tear film instability of dry eye patients. METHODS: Contrast sensitivity and optical aberrations were measured in 22 dry eye and 10 normal patients before and after daily use of artificial tears. The contrast sensitivity and optical aberrations were measured in response to the administration of a single drop of artificial tear placed in the eye. RESULTS: The short-term effect (i.e., a few minutes) of a single drop of artificial tear placed in the eye was a decrease in contrast sensitivity and an increase in optical aberrations. Long-term daily use of the artificial tears (i.e., up to 2 weeks) resulted in less of a short-term effect in dry eye patients. No long-term effect was observed for normal subjects. Both contrast sensitivity loss and optical aberrations decreased by 35% per week of artificial tear use for the dry eye patients suggesting that the changes in contrast sensitivity were the result of optical aberrations. CONCLUSIONS: The results suggest that the changes in contrast sensitivity with artificial tear administration were the result of optical aberrations. It appears that long-term use of artificial tears may normalize the tear layer of dry eye disease patients.

Accommodation response and visual discomfort.

Although visual discomfort symptoms associated with near work have been correlated with clinical measures of accommodation, studies using objective recordings have not found corresponding deficits in accommodative function. One problem with previous studies is that accommodation measures have been too brief to assess accommodative fatigue. This study examined steady state accommodative responses among a college population with visual discomfort, over a 90-s time period. Thirty-one participants were grouped into high (n = 15) or low visual discomfort groups (n = 16) based on their scores on the Conlon Visual Discomfort Survey. Using the WAM-5500 autorefractor, accommodation responses were recorded at 5 Hz for two consecutive minutes at five viewing distances. The results showed a significant interaction between the high and low discomfort groups over time in accommodation response. The high discomfort group showed an increase in accommodative lag, whereas the low discomfort group had a stable response. Our study suggests that the high visual discomfort group is characterized by accommodative fatigue, with a higher lag of accommodation developing at a near viewing distance over time.

Longitudinal study of visual discomfort symptoms in college students.

PURPOSE: To determine the variation of visual discomfort symptom reporting in a group of college students over a 1 year period. METHODS: Subjects were screened for visual acuity and uncorrected refractive error before participating in the study. A survey of visual discomfort developed by Conlon et al., Vis Cogn 1999;6:637-666, and the Convergence Insufficiency Symptom Survey (CISS) were administered to a group of 23 college students twice with approximately 1 year between administrations. All subjects also completed two clinical assessments of accommodation and vergence. RESULTS: The mean time between administrations of the symptom surveys was 13 months. There was no clinically significant mean difference between the first and second administration of both visual discomfort surveys. The intraclass correlation coefficient was 0.82 for the Conlon et al., Vis Cogn 1999;6:637-666 survey and 0.85 for the CISS. The 95% limits of agreement for the Conlon et al., Vis Cogn 1999;6:637-666 survey was -18.44, 17.92 and for the CISS was -14.36, 13.36. The intraclass correlation coefficient values for the optometric tests ranged from 0.38 to 0.83. CONCLUSIONS: Visual discomfort symptoms were found to be stable in the majority of young college students over a 1 year period. However, a minority of students showed large variability between the two administrations of the surveys.