Norman E. Leach

The diagnosis and characteristics of moderate dry eye in non-contact lens wearers

Purpose. To identify and characterize moderate dry eye in non–contact lens wearers with a new scoring system-based dry eye questionnaire and to determine which objective tests better differentiate patients with moderate dry eye from healthy patients. Methods. Fifty-two healthy subjects (21 women and 31 men with a mean age of 27.8 ± 9.2 years) and 37 subjects with moderate dry eye (33 women and 4 men with a mean age of 36.4 ± 12.9 years) completed a 42-item dry eye questionnaire. Seventeen healthy subjects (11 women and 6 men with a mean age of 30.5 ± 9.7 years) and 28 subjects with moderate dry eye (24 women and 4 men with a mean age of 38.50 ± 3.8 years) underwent additional objective assessment of ocular surface health, tear osmolality, tear stability, and tear volume. Results. Subjects with moderate dry eye scored significantly higher (49.8 ± 20.3, P<0.0001) on the dry eye questionnaire than did normal subjects (11.7 ± 10.3). Ocular irritation symptoms worsened with progression of time of day in both groups of subjects. Internal reliability (0.95 Cronbach α) was excellent, and concurrent validity (Spearman ρ 0.507) was acceptable when compared to the McMonnies and Ho dry eye questionnaire. Significant differences in tear osmolality (P<0.00001), invasive tear breakup time (P<0.034), and corneal vital dye staining (P<0.0001) were detected between the two groups of subjects. A stepwise linear regression on objective clinical tests, however, did not account for 77% of the total variance in the questionnaire scores. Conclusions. A unique scoring system-based dry eye questionnaire was validated to separate non–contact lens wearers with moderate dry eye from healthy subjects. Objective tests of tear osmolality and stability and ocular surface integrity were better than other clinical measures at identifying differences between the two subject groups. The results strongly support the evidence that the diagnosis and treatment of moderate dry eye requires a detailed assessment of self-perceived symptoms and that objective clinical testing alone may be insufficient.

Central and peripheral corneal thinning in keratoconus.

Purpose: Recent data regarding the mid-peripheral portion of the removed corneal button in transplant surgery indicate histopathologically that keratoconus was present also in the peripheral portion of the button. The intent of this study was therefore to investigate if peripheral changes could also be detected clinically by measuring the central and peripheral corneal thickness of KC patients. Methods: Corneal pachymetry was measured with the Visante optical coherence tomography and Orbscan II. Of 52 subjects, 26 were KC subjects and 26 were age- and sex-matched control subjects. Results: Corneal thickness, in KC patients, was significantly reduced in all areas compared with corneal thickness among controls with both the Visante optical coherence tomography and Orbscan II. Conclusion: The results of the present study have provided clinical evidence that KC is a disease affecting a wider area of the cornea. Although the KC cornea shows the greatest change in thickness in the ectatic region, this attenuation declines toward the periphery. The presence of peripheral thinning indicated that KC may be a “pancorneal” pathology and not limited to the ectatic portion.

Short- and Long-term Repeatability of Visioptic Alcon Eyemap (visioptic Eh-270) Corneal Topographer on Normal Human Corneas

The purpose of this study was to examine the short-term and long-term (6 months) repeatability of the Alcon EyeMap (Visioptic EH-270)a Computerized Corneal Topographer on normal eyes. Three measurements were taken on both eyes of 39 subjects with the corneal topographer. Both eyes of seven of these subjects were measured 6 months later in order to evaluate long-term repeatability. The data showed that short-term reliability of the instrument was acceptable with a mean standard deviation (SD) < or = 0.5 D up to 3 mm (6-mm optical zone) from the center of the normal cornea. Beyond that distance, SDs of repeated measures increased systematically, making the results less useful. Long-term repeatability of the instrument over a 6-month period was acceptable clinically, although statistically significant differences were noted.

Empirical Advanced Orthokeratology Through Corneal Topography: The University of Houston Clinical Study

Purpose. Traditionally, orthokeratology has used diagnostic lenses to determine the best fit. The purpose of this study was to determine the efficacy of fitting empirically from corneal topography, without the use of diagnostic lenses. Methods. Twenty-nine subjects, 18 to 37 years old, with myopia of 1.00 to 4.00 diopters (D) and astigmatism of no more than 1.50 D, were entered into this 6-month study. Corneal topography, scanning slit topography and corneal thickness (Orbscan), confocal microscopy, ultrasound corneal thickness, aberrometry, and biomicroscopy were used to assess corneal changes. Unaided logMAR high-contrast visual acuity, subjective refraction, and questionnaires were used to monitor vision and symptoms. Follow-up visits were scheduled after 1 day, 1 week, 2 weeks, 1 month, 3 months, and 6 months. Results. For 6-month data, unaided logMAR acuity improved from 0.78 ± 0.26 in the right eye and 0.75 ± 0.22 in the left eye to 0.06 ± 0.18 in the right eye and 0.04 ± 0.16 in the left eye. Myopia decreased from –2.55 ± 0.87 D in the right eye and −2.47 ± 0.89 D in the left eye to +0.45 ± 0.74 D in the right eye and −0.17 ± 0.69 D in the left eye. Shape factor, using corneal topography, increased from 0.85 ± 0.13 in the right eye and 0.85 ± 0.15 in the left eye to 1.28 ± 0.32 in the right eye and 1.30 ± 0.29 in the left eye. Both eyes showed a decrease in lower-order aberrations (i.e., defocus) and an increase in higher-order aberrations (i.e., spherical aberrations and coma). Conclusions. Myopia reduction after 1 week was clinically insignificant from the 1-month results, indicating that the full effect is achieved by 1 week. Neither total nor epithelial corneal thickness varied significantly from baseline measurements.

Reverse-geometry Gas-permeable Lens Design for Pellucid Marginal Degeneration

Purpose. To report a case of treating a patient with pellucid marginal degeneration (PMD) by using a reverse-geometry gas-permeable lens design. Methods. A 38-year-old Hispanic man was referred for having reduced visual acuity secondary to distorted corneas. The patient was diagnosed with PMD after an extensive slitlamp examination showed a thinning of the inferior peripheral cornea in both eyes. Corneal topography (Orbscan II) was performed to help confirm the diagnosis. A Reverse Aspheric Ortho Focus (RAOF) gas-permeable lens was fitted on this patient. Results. The Orbscan II corneal topography showed distinct peripheral steepening, a pronounced astigmatic pattern (greater in the left eye than in the right), and thinner corneas in the inferior periphery than centrally. The fluorescein pattern of the RAOF 5 lenses showed central alignment, good edge lift 360°, mid peripheral bearing with 0.5 mm vertical movement on blinking, and good centration. The patient’s distance visual acuity with the lenses was 20/20−1 in the right eye and 20/20 in the left. Conclusions. The Orbscan II was an important tool in making the diagnosis of early PMD, because few clinical signs were observed. Not only does the Orbscan II provide the clinician with a topographic map of the cornea, but it also measures the corneal thickness, which aided in the diagnosis of this patient. In addition, the posterior float measurement provided by the Orbscan II may be instrumental in making a differential diagnosis. A reverse-geometry gas-permeable lens provided the patient with improved peripheral fit over conventional designs, adequate comfort, and optimal visual acuity.

Contact Lens Daily Cleaner Efficacy: Multipurpose versus Single-Purpose Products

Abstract Multipurpose contact lens care products have been developed to provide wearers with simpler lens care regimens. Although previous studies have shown that the multipurpose products can be formulated without increasing the risk of irritation or other adverse reactions, questions still remain regarding the effectiveness of multipurpose products that are labeled with cleaning indications. The following is a report of a 3-month study conducted to compare two approved surfactant contact lens cleaning products (Bausch & Lomb® ReNu® Multi-Purpose Solution and Alcon® Opti-Clean® II Daily Cleaner) when used in the care of soft (hydrophilic) contact lenses worn for daily or extended wear. Patients (N = 181) used the study surfactant lens cleaning products in conjunction with their current lens care regimens in a paired-lens, left-eye/right-eye comparison. Quantitative analysis of lens protein uptake levels (ninhydrin test) and microscopic examination showed no significant differences between lenses cleaned with the ReNu Multi-Purpose Solution and the Opti-Clean II Daily cleaner. We conclude that the clinical performance of the ReNu Multi-Purpose Solution is equivalent to that of the Opti-Clean II Daily Cleaner.

Monocular vs. Stereoscopic Measurement of Cup-to-disc Ratios

Stereoscopic viewing of the optic nerve head and cup has been reported to provide more reliable cup-to-disc (C/D) ratio estimates. We investigated the variability in C/D ratio estimates among three experienced optometric clinicians using conventional direct ophthalmoscopy and indirect biomicroscopy with the Volk 90 D lens. The pupils of 21 subjects were dilated and the discs assessed randomly by each examiner for the determination of the C/D ratio. Analysis of variance indicates that the two methods are not significantly different from each other when comparing interexaminer reliability. However, for a particular examiner, one method may be more effective than the other.

Vertical imbalance induced by prism-ballasted soft toric contact lenses fitted unilaterally.

Fitting a prism‐ballasted soft toric contact lens unilaterally may potentially induce a vergence error that the subject cannot compensate. In the present study, a prism‐ballasted (1.5Δ base down) soft toric contact lens was fitted in the right eye only of 10 subjects with normal binocular vision. The effect on binocular vision was evaluated by measuring vertical phoria adaptation and vertical fixation disparity adaptation. The results show that the vertical vergence error induced was well compensated and fully adapted to. However, care might be needed when fitting these lenses unilaterally in subjects with vertical phoria‐related problems.

Morphology of contact lens-induced conjunctival epithelial flaps: A pilot study

PURPOSE Conjunctival epithelial flap (CEF) is a conjunctival condition most commonly seen in silicone hydrogel contact lens wearers. This study utilized impression cytology to investigate the cellular composition and health of CEFs. METHODS Nine (9) subjects were enrolled - 3 non-lens wearers, 3 contact lens wearers without CEF, and 3 contact lens wearers with CEFs wearing 8.4/13.8 lotrafilcon A lenses. Impression cytology samples were collected from the flap or similar locations, if CEF was absent, using rectangular 5 mm × 2 mm Millipore HAWP02500 membrane filters. The filters were gently pressed onto the conjunctiva, subsequently fixed in 95% alcohol, stained with hematoxylin-eosin and evaluated under an Olympus IX70 microscope. Measurements of the longest cell and nucleus dimensions were measured on 40 cells from each filter by utilizing NIH Image 1.63. RESULTS CEF consisted of multilayers of epithelial and goblet cells and were devoid of inflammatory cells, basement membrane material and stromal tissue. The cytoplasmic and nuclear dimensions were similar within the groups and the cytoplasm-to-nucleus ratio was not different between the flap group and the non-lens wearing group. CONCLUSION The CEF appeared to be formed by healthy epithelial and goblet cells that have been dislocated from their normal location along the conjunctival surface by the lens edge. No inflammatory cells were present in this contact lens induced condition, which is reported to be associated most commonly with the silicone hydrogel material.

Rigid lens base curve stability upon hydrogen peroxide disinfection.

Because of the possibility of transmitting communicable diseases, in particular the HIV virus, it has been recommended that all diagnostic contact lenses, including rigid lenses, be disinfected after each use. Hydrogen peroxide is a recommended disinfection agent, but its effect on rigid lens polymers is relatively unknown. We soaked 50 lenses of 5 different polymers in 3% hydrogen peroxide for 10 min and measured the base curves to determine if any changes occurred. Our results showed no statistically significant change in base curve for the lenses measured, but 22% of the lenses did exhibit a small amount of warpage (mean 0.0382 mm) of the base curve. We were not able to determine what caused these lenses, and not all the lenses, to warp. Under the conditions of this study, hydrogen peroxide does not appear to cause clinically significant parameter changes, but lenses should be checked for warpage before use.