The role of ethnicity versus environment in tear film stability: A pilot study.

PURPOSE: Existing literatures suggest a difference in tear film stability between Caucasian and Asian ethnic groups. However, such a finding was compounded by the fact that the comparison was done on subjects living in different environments. Therefore, it is not clear whether such difference is due to ethnicity, environment, or both. The aim of this study is to clarify the roles of these two factors. METHODS: A total of 88 asymptomatic subjects participated in this present study. For each subject, the tear film break-up time (TBUT), non-invasive TBUT (NITBUT) and tear meniscus height (TMH) were measured. To isolate the effect of ethnicity, the results of 12 American Asian young adults were compared against the results of 23 Caucasian adults. Both groups were recruited from Nova Southeastern University. To elucidate the effect of environment, the results from the same 12 American Asians were compared to that of the 53 Asian young adults recruited from the Tianjin Vocational Institute, China (Tianjin Asian). RESULTS: The tear film stability did not show significant difference among American Asian subjects and Caucasian subjects in TBUT (10.49 ± 2.86 s vs. 11.06 ± 2.79 s,p = 0.57), NITBUT (11.19 ± 4.89 s vs. 11.14 ± 6.20 s, p = 0.98), and TMH (0.21 ± 0.08 mm vs. 0.22 ± 0.05 mm, p =0.59). However, the tear film stability was significantly better in the American Asian group than the Tianjin Asian group in TBUT (10.49 ± 2.86 s vs. 7.60 ± 3.26 s, p = 0.01), NITBUT (11.19 ± 4.89 s vs. 8.03 ± 3.56 s, p = 0.01), and TMH (0.21 ± 0.08 mm vs. 0.14 ± 0.03 mm, p < 0.01). CONCLUSIONS: The previously reported difference in Caucasian and Asian populations might be due to the fact that the studied subjects have different living environments.

Randomized controlled trial of electro-stimulation therapies to modulate retinal blood flow and visual function in retinitis pigmentosa.

PURPOSE: We examined changes in visual function and ocular and retinal blood flow (RBF) among retinitis pigmentosa (RP) participants in a randomized controlled trial of electro-stimulation therapies. METHODS: Twenty-one RP participants were randomized (1:1:1) to transcorneal electrical stimulation (TES) at 6 weekly half-hour sessions, electro-acupuncture or inactive laser acupuncture (sham control) at 10 half-hour sessions over 2 weeks. Early Treatment of Diabetic Retinopathy Study (ETDRS) visual acuity (VA), quick contrast sensitivity function, Goldmann visual fields, AdaptDx scotopic sensitivity, spectral flow and colour Doppler imaging of the central retinal artery (CRA), and RBF in macular capillaries were measured twice pre-treatment, after 2 TES sessions, within a week and a month after intervention completion. RESULTS: We measured a significant improvement in retrobulbar CRA mean flow velocity for both the TES (p = 0.038) and electro-acupuncture groups (p = 0.001) on average after 2 weeks of treatment when compared to sham controls. Transcorneal electrical simulation (TES) and electro-acupuncture subjects had significant 55% and 34% greater increases, respectively, in RBF in the macular vessels when compared to sham controls (p < 0.001; p = 0.008) within a week of completing six TES sessions or a month after electro-acupuncture. There was a significant difference in the proportion of eyes that had improved visual function when comparing the three intervention groups (p = 0.038): four of seven TES subjects (57%), two of seven electro-acupuncture subjects (29%) and none of the seven control subjects (0%) had a significant visual improvement outside of typical test-retest variability at two consecutive post-treatment visits. CONCLUSION: Increased blood flow following electro-stimulation therapies is an objective, physiological change that occurred in addition to visual function improvements in some RP patients.

Longevity of visual improvements following transcorneal electrical stimulation and efficacy of retreatment in three individuals with retinitis pigmentosa.

PURPOSE: A small-scale randomized controlled trial conducted by our group found that four of seven retinitis pigmentosa (RP) subjects who received six weekly Transcorneal Electrical Stimulation (TES) sessions developed significant improvements in visual acuity (VA), quick contrast sensitivity function (qCSF), and/or Goldmann visual fields (GVF). We longitudinally monitored three of these participants for declining visual function due to natural RP progression to determine the duration of their responses and administered retreatments. METHODS: Over a period of 29-35 months, repeated ETDRS VA, qCSF and/or GVF tests and three to six TES treatment courses consisting of six weekly sessions were administered in each eye of three RP participants every four to 16 months in an unmasked, prospective case series study. RESULTS: For two participants, there were significant VA improvements of 44-52 letters (0.88-1.04 logMAR) and 15-23 letters (0.3-0.46 logMAR) in the worse eye at baseline after each of three or four treatment courses of TES compared to initial baseline. They had no significant decreases from baseline for VA or qCSF over 29 to 35 months, The third participant had a significant mean improvement in VA in the eye with better baseline vision (p = 0.004) and binocularly (p < 0.001) following six treatment courses over the 29-month period. For the first two participants, mean annual rates of GVF change for each eye ranged from -5% to 0% with the V4e stimulus, and -26% to +33% the III4e stimulus. The third participant's mean annual GVF changes were +14 to +35%, with a statistically significant improvement across 29 months for both the V4e and III4e stimuli in the right eye (p = 0.045; p = 0.015) and the V4e stimulus in the left eye (p = 0.047). CONCLUSION: Following encouraging visual improvements after TES that lasted for several months, it appears it may be possible to restore and prevent slowly diminishing vision over time with retreatments, which requires confirmation in a large-scale randomized controlled trial.

Neuro-ophthalmic manifestations of a complicated cholesteatoma.

BACKGROUND: A cholesteatoma, also known as an epithelioma, is a mass of soft tissue that results from the accumulation of keratin protein debris enclosed by a layer of stratified squamous epithelium. CASE REPORT: A patient with cholesteatoma surrounding both internal carotid arteries presented with cerebral ischemic symptoms expressed as visual and ocular symptoms. Because of its location, mass effect, and potential stenosis of the internal carotids, this slow-growing tumor is potentially sight threatening. Asymmetric cupping of the optic nerves associated with symptoms such as dizziness, diplopia, or facial pain should be worked up carefully. CONCLUSION: The primary care optometrist can play an important role in the diagnosis and continued management of a patient with a cholesteatoma, carefully monitoring early signs of progression or change. This case illustrates how an intracranial lesion, away from the eye, can impact a number of ocular and visual functions.

Optimal dioptric value of near addition lenses intended to slow myopic progression.

PURPOSE: The purpose of this study was to determine the optimal power value of near addition lenses, which would create the least error in accommodative and vergence responses. METHODS: We evaluated accommodative response, phoria, and fixation disparity when the subject viewed through various addition lenses at three working distances for 30 young adults (11 emmetropic, 17 myopic, and 2 hyperopic). Accommodative response was determined with a Canon R-1 infrared optometer under binocular viewing conditions, phoria was determined by the alternating cover test with prism neutralization, and fixation disparity was measured with a Sheedy disparometer. RESULTS: We found that the optimal powers of near addition lenses for the young adult subjects associated with zero retinal defocus were +0.92 D, +1.04 D, and +1.28 D at three viewing distances, 50 cm, 40 cm, and 30 cm, respectively. The optimal powers associated with -3 prism diopters (Delta) near phoria were +0.58 D, +0.35 D, and +0.20 D at the three distances, 50 cm, 40 cm, and 30 cm, respectively. In addition, we found high correlations between the initial accommodative error and the optimal power of the near addition lenses and between the initial near phoria and the optimal power of the near addition lenses. CONCLUSIONS: The results suggest that when the effects of near addition lenses on the accommodative and vergence systems are both considered, the optimal dioptric power of the near addition lens is in a range between +0.20 D and +1.28 D for the three viewing distances. Using progressive lenses to delay the progression of myopia may have promising results if each subject's prescription is customized based on establishing a balance between the accommodative and vergence systems. Formulas derived from this study provide a basis for such considerations.