Carl J. Bassi

Optic nerve damage in Alzheimer's disease.

Optic nerves from ten patients with Alzheimers disease were histologically examined and compared with those from age-matched controls. Specific and nonspecific measures of degeneration were noted in eight of ten Alzheimers disease optic nerves; no degeneration was noted in any of the controls. Results of histologic examination of the retinas of one eye of three Alzheimers disease patients also showed degeneration of retinal ganglion cells and their axons in the nerve fiber layer. Morphometric analysis suggested that in many cases of Alzheimers disease, the optic nerve showed predominant loss of the largest class of retinal ganglion cells (M-cells) that contribute large caliber fibers to the optic nerve. The M-cell system is known to mediate specific visual functions, and selective involvement of the M-cell population leads to clinically measurable neuro-ophthalmic and psychophysical impairments in many Alzheimers disease patients.

Binocular Visual Impairment in Glaucoma

Monocular and binocular vision was assessed in patients with glaucoma (n = 21), in patients with ocular hypertension (n = 20), and in age-matched visual control subjects (n = 20) using three tests: color vision with the Lanthony Desaturated D-15 test, low spatial frequency contrast sensitivity with the Pelli-Robson chart, and stereoacuity with the RANDOT test. No significant differences were found among the groups in the severity or type of color vision loss. Monocular contrast sensitivity testing showed considerable overlap among groups but a significant loss of contrast sensitivity in the glaucoma patients relative to ocular hypertensives and control subjects. Binocular testing also showed a significant loss of contrast sensitivity in the glaucoma patients compared with both the ocular hypertensives and the control subjects. Stereoacuity also was significantly impaired in the glaucoma patients. These results indicate that two tests of binocular function, stereoacuity and binocular contrast sensitivity testing, may have utility in identifying early glaucomatous damage.

A comparison of the short-term settling of three scleral lens designs.

Purpose Scleral gas-permeable lenses are rapidly gaining international popularity. Unlike corneal gas-permeable lenses, scleral lenses are fitted to the bulbar conjunctiva and settle into the tissue after insertion. To date, we are unaware of any studies examining the settling behavior of three varying scleral lens designs. The purpose of this study was to quantify the mean total settling and mean rates of settling for three scleral lens designs: Onefit P&A (Blanchard Contact Lens, Inc), Mini Scleral Design (msd) (Blanchard Contact Lens, Inc), and Jupiter (Visionary Optics). Methods A randomized, repeated-measures study of Onefit P&A, msd, and Jupiter was performed. Subjects were fitted from a trial lens set, according to the manufacturer’s guidelines. After insertion, lens settling was measured at 0 minutes, 15 minutes, 30 minutes, 45 minutes, 1 hour, 2 hours, 4 hours, 6 hours, and 8 hours. Statistical analyses were performed using analysis of variance and two-stage, nonlinear regression analyses of settling over time. Results On average, the Onefit P&A, msd, and Jupiter lenses settled a total of 113.7, 133.7, and 88.1 &mgr;m, respectively. Although the rates of settling were not linear, analysis of variance revealed a significant difference in the average settling rates (p < 0.05) among the groups. Tukey analyses revealed a significant difference in the settling rates for msd and Jupiter comparison (p < 0.05). Nonlinear regression analyses predicted that the lenses settled to about 80% of the final estimated values for the Onefit P&A lens, 90% for msd, and 99% for the Jupiter, after 8 hours. Conclusion We concluded that the amount of settling varied significantly among the three lens designs. Settling rates were greatest shortly after insertion. Larger lenses were estimated to be settled by 8 hours. Based on the results of this short-term study, careful consideration to the settling patterns of individual scleral lens designs should be given.

Review of the Visual System in Parkinson's Disease

In an era when the prevalence of Parkinsons disease (PD) is increasing because our population is aging, eye care professionals need to become aware of the visual changes experienced by PD patients. This paper reviews the visual pathophysiology of PD and the results of the lack of dopamine on the retina and visual cortex. It also discusses the impact of PD on the oculomotor system and the visual sensory pathways with the consequent effects on reading, balance, and driving abilities of PD patients. Further research on the visual system and PD may provide improved means for early diagnostic testing as well as the possibility of vision rehabilitation for treatment of visual performance impairments.

Effect of topical anesthetic use on initial patient satisfaction and overall success with rigid gas permeable contact lenses.

Background. Rigid gas permeable (RGP) contact lenses have numerous benefits; however, RGP lens use is not increasing in the United States. An important factor for this trend has been initial comfort. Studies have demonstrated that how RGPs are presented to patients, in addition to lens design, can play an important role in the initial comfort process. Another important factor could be the use of a topical anesthetic during the fitting and dispensing visits. The purpose of this study was to use a multicenter format to determine if topical anesthetic use increased the likelihood of patient satisfaction and success. Methods. A total of 80 subjects, with no previous rigid lens wear experience, was entered into this 1 -month study, including 20 subjects from each of 4 institutions. Subjects were randomly divided into the following two groups: (A) anesthetic or (B) placebo, with the former group receiving one drop of a topical anesthetic before lens insertion at both the diagnostic fitting and dispensing visits, whereas the latter group received a placebo. Subjects completed a questionnaire on their perception of rigid lens wear both immediately before fitting and at the 1-month visit. After diagnostic fitting with rigid lenses, subjects completed an adaptation questionnaire after 15 min, 1 week, 2 weeks, and 1 month of lens wear. Results. Seventy of the 80 subjects completed the study and, of the 10 subjects who discontinued, 8 were in the placebo group. In all categories evaluated, the anesthetic group experienced a more optimum adaptation experience at each visit vs. the placebo group. Specifically, overall comfort was rated significantly higher at both dispensing and 2 weeks. In addition, the anesthetic group exhibited significantly greater overall satisfaction with rigid lens wear at 2 and 4 weeks. Also, the anesthetic group perceived their adaptation, sensitivity, and adaptation time to be significantly better at the 1 -month visit. There was no significant difference in corneal staining between these two groups at each visit, with the exception of a greater amount of staining in the central quadrant for the placebo group at the 1 -month visit. Conclusions. The use of a topical anesthetic at the fitting and dispensing visits for first-time wearers of RGP lenses resulted in significantly fewer dropouts, improved initial comfort, an enhanced perception of the adaptation process, and greater overall satisfaction after 1 month of lens wear as compared to the use of a nonanesthetizing placebo at those visits. This result, in combination with both presenting RGP lenses in a nonthreatening manner and optimizing the lens design and fitting relationship, should result in a positive adaptation process and successful wear of RGP contact lenses.

Effect of patient personality profile and verbal presentation on successful rigid contact lens adaptation, satisfaction and compliance.

Background. Rigid gas permeable (RGP) lenses have numerous benefits, including quality of vision, ocular health, and reduction of myopic progression in young people. Nevertheless, RGP lens use is not increasing in the United States. It is possible that certain patient personality characteristics and/or how a practitioner presents RGP lenses to a new patient may affect satisfaction and success. The purpose of this study was to evaluate the effect of individual patients personality and the practitioners method of presenting RGP lenses to new patients on their ability to adapt to these lenses. Methods. Forty-nine subjects, all noncontact lens wearers, were entered into this 1-month study, which was conducted at both the University of Missouri-St. Louis School of Optometry and the Pacific University College of Optometry. All subjects initially completed standardized questionnaires pertaining to locus of control, openness to new experiences, and motivation/expectations. After diagnostic fitting with a RGP lens material, the subjects were placed into one of the following three groups: (1) Fear-Arousing Non-Enthused; (2) Neutral Content Non-Enthused; or (3) Neutral Content Enthused. They observed one of three video presentations on RGP lens wear. Subjects submitted daily questionnaires providing their evaluation of such factors as comfort, wearing time, and handling. Results. The results showed that there was a significant difference (x2=6.99; p<0.05) among the different groups in the number of dropouts: 6/19 with the Fear-Arousing Non-Enthused group, 2/17 with the Neutral Content Non-Enthused group, and 0/13 with the Neutral Content Enthused group. There was also a significant difference (ANOVA F=4.1, p<0.05) among the groups on compliance, with the Neutral Content Enthused group demonstrating greater compliance. In terms of satisfaction, there was no significant difference among presentation groups. Conclusion. It was concluded that the method of presentation is important for successful RGP contact lens wear. If presented with genuine interest and a positive and realistic attitude, patients are more likely to succeed in RGP lens wear during the initial critical period.

Macular pigment spatial distribution effects on glare disability

PURPOSE This project explored the relationship of the macular pigment optical density (MPOD) spatial profile with measures of glare disability (GD) across the macula. METHODS A novel device was used to measure MPOD across the central 16° of retina along four radii using customized heterochromatic flicker photometry (cHFP)at eccentricities of 0°, 2°, 4°, 6° and 8°. MPOD was measured as discrete and integrated values at all measured retinal loci. GD was calculated as a difference in contrast sensitivity (CS) between no glare and glare conditions using identical stimuli presented at the same eccentricities. GD was defined as [(CSNo Glare-CSGlare)/CSNo Glare] in order to isolate the glare attenuation effects of MPOD by controlling for CS variability among the subject sample. Correlations of the discrete and integrated MPOD with GD were compared. RESULTS The cHFP identified reliable MPOD spatial distribution maps demonstrating a 1st-order exponential decay as a function of increasing eccentricity. There was a significant negative correlation between both measures of foveal MPOD and GD using 6 cycles per degree (cpd) and 9 cpd stimuli. Significant correlations were found between corresponding parafoveal MPOD measures and GD at 2 and 4° of eccentricity using 9 cpd stimuli with greater MPOD associated with less glare disability. CONCLUSIONS These results are consistent with the glare attenuation effects of MP at higher spatial frequencies and support the hypothesis that discrete and integrated measures of MPOD have similar correlations with glare attenuation effects across the macula. Additionally, peak foveal MPOD appears to influence GD across the macula.

Central serous chorioretinopathy produces macular pigment profile changes.

Purpose Macular pigment (MP) is the collective name for three isomeric carotenoids: lutein, zeaxanthin, and meso-zeaxanthin. Macular pigment density is greatest in the central retina, peaking at the fovea and falling to negligible levels at 7 degrees of eccentricity from the fovea. Several studies have documented the interocular symmetry of MP optical density (MPOD) spatial distribution. The ongoing University of Missouri–St. Louis study uses a novel, customized heterochromatic flicker photometer to map the spatial distribution of MPOD up to 8 degrees of eccentricity relative to the fovea. Here, we report the MPOD measurements in a subject with resolved central serous chorioretinopathy (CSC) in the right eye. Case Report Two subjects performed the full MPOD spatial mapping. The test subject (WK) had a history of central serous CSC of the right eye. The control subject (CP) had an unremarkable ocular health history. Comprehensive exams were performed on each subject including Cirrus optical coherence tomography imaging and fundus photographs. Subject CP showed highly symmetric interocular MPOD profiles at the fovea and 2, 4, and 6 degrees of eccentricity. Subject WK showed interocular asymmetry at the fovea and at 2 degrees with relative symmetry at 4 and 6 degrees. A paired sample t test identified nonsignificant interocular values for subject CP and statistically significant differences of at 2 degrees for subject WK. Conclusions We hypothesize that subject WK’s interocular MPOD spatial distribution asymmetry resulted from his history of resolved CSC. This asymmetry is statistically significant at 2 degrees of retinal eccentricity and corresponds to the extent of retinal pigment epithelium changes observed on the fundus photographs. These findings suggest that MP and retinal pigment epithelium changes after a CSC episode are comparable in the area of the retina affected. These disruptions may also be measureable in other macular conditions in which the sensory retina is affected (e.g., cystoid macular edema and clinically significant macular edema).

An evaluation of the 8.4 mm and the 8.8 mm base curve radii in the Ciba NewVe vs. the Vistakon Acuvue

Abstract As practitioners, we have often fit soft contact lenses using the medium or flattest base curve radius as our first choice of base curve radius; however, it is important to realize that identical base curve radii in different lens materials may fit differently. In addition, the flattest or medium base curve radius may not always provide optimal comfort. When fitting soft lenses, it is important to achieve a good fit and provide good performance. In this study, completed at the University of Missouri-St. Louis, School of Optometry, the NewVue (Ciba Vision Corp.) and the Acuvue (Vistakon) 8.4 and 8.8 mm base curve radii were compared based on comfort, visual acuity, contrast sensitivity, lens movement, and ease of handling in a double-blind study. The results showed that subjects performed similarly among NewVue and Acuvue lenses. The Acuvue 8.4 mm base curve radius was perceived as being more comfortable than the patients current contact lenses and showed optimal centration and best distance Snellen visual acuity. The Acuvue 8.8 mm base curve radius showed optimal lens movement. The NewVue 8.4 mm base curve radius showed optimal lens movement and demonstrated excellent handling and lens centration. The NewVue 8.8 mm base curve radius demonstrated excellent lens handling. When fitting a disposable contact lens candidate, our first choice for lens selection would be the Acuvue 8.8 mm base curve radius or the NewVue 8.4 mm base curve radius. If these lenses are not adequate, appropriate changes may be made.

Influence of macular pigment optical density spatial distribution on intraocular scatter

Purpose This study evaluated the summed measures of macular pigment optical density (MPOD) spatial distribution and their effects on intraocular scatter using a commercially available device (C-Quant, Oculus, USA). Methods A customized heterochromatic flicker photometer (cHFP) device was used to measure MPOD spatial distribution across the central 16° using a 1° stimulus. MPOD was calculated as a discrete measure and summed measures across the central 1°, 3.3°, 10° and 16° diameters. Intraocular scatter was determined as a mean of 5 trials in which reliability and repeatability measures were met using the C-Quant. MPOD spatial distribution maps were constructed and the effects of both discrete and summed values on intraocular scatter were examined. Results Spatial mapping identified mean values for discrete MPOD [0.32 (s.d. = 0.08)], MPOD summed across central 1° [0.37 (s.d. = 0.11)], MPOD summed across central 3.3° [0.85 (s.d. = 0.20)], MPOD summed across central 10° [1.60 (s.d. = 0.35)] and MPOD summed across central 16° [1.78 (s.d. = 0.39)]. Mean intraocular scatter was 0.83 (s.d. = 0.16) log units. While there were consistent trends for an inverse relationship between MPOD and scatter, these relationships were not statistically significant. Correlations between the highest and lowest quartiles of MPOD within the central 1° were near significance. Conclusions While there was an overall trend of decreased intraocular forward scatter with increased MPOD consistent with selective short wavelength visible light attenuation, neither discrete nor summed values of MPOD significantly influence intraocular scatter as measured by the C-Quant device.