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Biomedical subjects

G Lynn Mitchell

Publications and source records attributed to G Lynn Mitchell.

At least 19 recordsLinked to original sources
PubMed2006

Factors influencing the measurement of oxygen shortfall of the human cornea: sequencing of test conditions.

PURPOSE: The effects of sequencing of test conditions, in this case contact lens thicknesses, on the measurement of the oxygen shortfall of human corneas were studied. METHODS: Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode on the central, unanesthetized right corneas of 14 human subjects. Measurements were made under the following conditions: (1) the normal open eye; (2) after 5 min of static (without blinking) wear of each of seven rigid gas permeable lenses of seven center thicknesses (0.18, 0.12, 0.16, 0.20, 0.24, 0.28, and 0.32 mm); (3) after 5 min of static wear of a polymethylmethacrylate (PMMA) contact lens. Lens thicknesses were randomly assigned numbers, which were sequenced in seven cycles. Two subjects were assigned to each sequencing cycle, and each subject participated in two identical sessions. RESULTS: The interaction of order x thickness was determined to be insignificant (F=0.99; p=0.5101). The effect of lens order was also insignificant (F=0.76; p=0.6239), indicating that the order of lens placement did not affect the measured corneal oxygen shortfall. Not surprisingly, the analysis indicated a significant effect of lens thickness on corneal oxygen shortfall (F=3.94; p=0.0032). CONCLUSIONS: The sequencing of lenses of various thicknesses on the cornea does not affect the measurement of corneal oxygen shortfall.

Adult↗
PubMed2006

Reliability of grading lissamine green conjunctival staining.

PURPOSE: To assess the reliability of a lissamine green grading scale for conjunctival images. METHODS: A 20-second video clip of the right eye of 288 contact lens-wearing individuals was recorded using a digital slip-lamp camera after instilling liquid lissamine green. A single nasal and temporal still image were selected. A masked reader used the Oxford grading scale to grade the images on two occasions whereas a second masked reader graded each image on 1 occasion. kappa statistics and 95% confidence intervals (CIs) were used to determine the within- and between-grader reliability overall and when the sample was stratified by age, sex, contact lens type, and disease severity. RESULTS: There was substantial within-grader reliability for both the nasal (kappasimple = 0.69, 95% CI, 0.63-0.75) and temporal (kappasimple = 0.73, 95% CI, 0.67-0.79) images. There was moderate between-grader reliability for both the nasal (kappasimple = 0.51, 95% CI, 0.44-0.58) and temporal (kappasimple = 0.51, 95% CI, 0.44-0.58) images. Age, sex, and contact lens type did not affect within- or between-examiner reliability. There may have been an influence of disease severity on within-examiner reliability, because grading of the temporal images was significantly less reliable in the images with more significant staining. CONCLUSION: Within- and between-grader reliability of lissamine green staining seems to be at least substantial to moderate. Because the extent of conjunctival staining may influence reliability, this should be considered when studies may include patients with significant staining.

Adult↗
PubMed2006

Relation between mood and self-reported dry eye in contact lens wearers.

PURPOSE: The etiology of dry eye disease is poorly understood, and a significant percentage of the population reports experiencing frequent and burdensome symptoms. Recent evidence from other disciplines has shown a relation between self-rated mood and symptom reporting, and the purpose of this work was to explore the relation between self-rated mood and dry eye symptoms. METHODS: A cross-sectional/nested case-control study was used to examine factors associated with self-reported dry eye disease. Logistic and linear regression analyses were used to examine the relation between self-reported dry eye and positive and negative affect. All models included age, sex, education, income, race, and marital status, when appropriate. RESULTS: Four hundred fifteen individuals were enrolled in the study. Two thirds were women, and the average age was 30.6 +/- 11.2 (SD) years. Two hundred fifteen (51.8%) self-reported dry eye. The average positive-affect scores were 34.6 +/- 5.9 and 34.9 +/- 6.0 (t = 0.58, P = 0.56) for those self-reporting dry eye and not reporting dry eye, respectively. The average negative-affect scores were 19.4 +/- 6.0 and 18.6 +/- 5.7 (t = -1.38, P = 0.17) for the dry eye and non-dry eye groups, respectively. After controlling for age, neither logistic regression nor linear regression showed a relation between positive or negative affect and self-reported dry eye. CONCLUSION: Preliminary analyses suggest that self-reported mood is not related to dry eye status in contact lens wearers. Although symptoms are a hallmark of dry eye disease, they may not be significant enough such that they relate to affective states in the way they do for other symptomatic diseases with more associated pain (eg, arthritis).

Adult↗
PubMed2006

Comparison of multifocal and monovision soft contact lens corrections in patients with low-astigmatic presbyopia.

PURPOSE: The purpose of this study was to assess visual performance and patient satisfaction with two presbyopic soft contact lens modalities. METHODS: A crossover study of 38 patients with presbyopia was conducted. Patients were randomized first into either multifocal (Bausch & Lomb SofLens Multifocal) or monovision (SofLens 59) for 1 month. Visual performance was measured with high- and low-contrast visual acuity at distance and near and near stereoacuity. Patients' satisfaction was measured by the National Eye Institute Refractive Error Quality of Life Instrument questionnaire and by recording the patient's final lens preference. RESULTS: Patients maintained at least 20/20 binocular vision with both multifocal (MF) and monovision (MV) contact lenses under high-contrast conditions at distance and near. Under low-contrast conditions, patients lost less than a line of vision from the best spectacle correction to either multifocal or monovision contact lens correction at distance (pMF = 0.001, pMV = 0.006). Under low-contrast conditions at near, multifocal wearers lost five to six letters and monovision wearers lost two letters of vision (pMF < 0.001, pMV = 0.03, pMF/MV = 0.005). The average stereoacuity decreased by 79 s arc with monovision vs. multifocal contact lenses (p = 0.002). On the NEI-RQL, patients reported worse clarity of vision (pMF = 0.01, pMV < 0.001), more symptoms (pMF = 0.09, pMV = 0.01), and an improvement in their appearance with contact lens wear (pMF < 0.001, pMV < 0.001). Seventy-six percent of patients reported that they preferred multifocal contact lenses, and 24% preferred monovision contact lenses (p = 0.001). CONCLUSION: The majority of our patients preferred multifocals to monovision, most likely because the Bausch & Lomb SofLens Multifocal provides excellent visual acuity without compromising stereoacuity to the same degree as monovision.

Adult↗
PubMed2006

The effect of overnight contact lens corneal reshaping on refractive error-specific quality of life.

PURPOSE: The purpose of this study is to determine the effect of corneal refractive therapy (CRT) on refractive error-specific quality of life. METHODS: The National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) was administered to 20 myopic patients (mean spherical equivalent -3.11 D +/- 0.96 D) between the ages of 21 and 37 years both before and 1 month after being successfully fit with Paragon CRT lenses. High- and low-contrast best-corrected visual acuity (BCVA) and higher-order aberrations were also measured. Scores for the 13 NEI RQL-42 subscales were calculated and a Wilcoxon sign rank test was used to determine whether there was a significant change in each of the subscale scores. Post hoc power analyses were also performed. RESULTS: Statistically significant changes were found in three of the 13 NEI RQL-42 subscales. Significant improvements in subscale score were found for the symptoms (mean +/- standard deviation, 10.18 +/- 10.57, p = 0.0007) and dependence on correction (43.13 +/- 27.42, p < 0.0001) subscales. A significant reduction was found in the glare subscale (-32.50 +/- 35.22, p = 0.001). No significant changes were found in the clarity of vision, expectations, near vision, far vision, diurnal fluctuations, activity limitations, worry, suboptimal correction, appearance, or satisfaction with correction subscales. CONCLUSIONS: CRT may improve a patient's perception of their visual independence, decrease the amount of ocular symptoms they report, and increase symptoms of glare. A larger, well-controlled clinical trial is necessary to verify these results. An increase in patient-reported glare is likely the result of measured increases in higher-order aberrations after CRT, especially spherical aberration under mesopic and scotopic conditions.

Adult↗
PubMed2006

The Study of Progression of Adult Nearsightedness (SPAN): design and baseline characteristics.

PURPOSE: The Study of Progression of Adult Nearsightedness (SPAN) is a 5-year observational study to determine the risk factors associated with adult myopia progression. Candidate risk factors include: a high proportion of time spent performing near tasks, performing near tasks at a close distance, high accommodative convergence/accommodation (AC/A) ratio, and high accommodative lag. METHODS: Subjects between 25 and 35 years of age, with at least -0.50 D spherical equivalent of myopia (cycloplegic autorefraction), were recruited from the faculty and staff of The Ohio State University. Progression is defined as an increase in myopia of at least -0.75 D spherical equivalent as determined by cycloplegic autorefraction. Annual testing includes visual acuity, noncycloplegic autorefraction and autokeratometry, phoria, accommodative lag, response AC/A ratio, cycloplegic autorefraction, videophakometry, ultrasound, and partial coherence interferometry (IOLMaster). Participants' near activities were assessed using the experience sampling method (ESM). Subjects carried a pager for two 1-week periods and were paged randomly throughout the day. Each time they were paged, they dialed into an automated telephone survey and reported their visual activity at that time. From these responses, the proportion of time spent performing near work was estimated. RESULTS: Three-hundred ninety-six subjects were enrolled in SPAN. The mean (+/- standard deviation) age at baseline was 30.7 +/- 3.5 years, 66% were female, 80% were white, 11% were black, and 8% were Asian/Pacific Islander. The mean level of myopia (spherical equivalent) was -3.54 +/- 1.77 D, the mean axial length by IOLMaster was 24.6 +/- 1.1 mm, and subjects were 1.7 +/- 4.0 Delta exophoric. Refractive error was associated with the number of myopic parents (F = 3.83, p = 0.023), and the number of myopic parents was associated with the age of myopia onset (chi2 = 13.78, p = 0.001). In a multivariate analysis, onset of myopia (early vs. late) still had a significant effect on degree of myopia (F = 115.1, p < 0.001), but the number of myopic parents was no longer significant (F = 0.65, p = 0.52). For the ESM, the most frequently reported visual task was computer use (mean, 18.9%; range, 0-60.0%) and, overall, subjects reported near work activity 34.1% of the time (range, 0-67.3%). CONCLUSIONS: The design of SPAN and the baseline characteristics of the cohort have been described. Parental history of myopia is related to the degree of myopia at baseline, but this effect is mediated by the age of onset of myopia.

Accommodation, Ocular↗
PubMed2006

Rigid gas-permeable contact lens base curve radius and transmissibility effects on corneal oxygen uptake.

PURPOSE: The purpose of this study is to determine the effects of rigid gas-permeable contact lens thickness, base curve radius, and material permeability on corneal hypoxic stress. METHODS: Corneal oxygen uptake rates were measured with a Clark-type polarographic electrode on the right eye of 10 human subjects for the normal open eye (air) and after 5 minutes of static wear of rigid contact lenses of four cornea-to-contact lens base curve fitting relationships: 0.2 mm steeper-than-K (STK), 0.1 mm STK, on K, and 0.1 mm flatter-than-K (FTK). There were also four materials (polymethylmethacrylate [Dk=0], lotifocon B [OP-2, Dk=15.9], lotifocon A [OP-3, Dk=30], lotifocon C [OP-6; Dk=60]) and three center thicknesses (0.14, 0.28, and 0.53 mm for the OP-6 lenses and 0.14 mm for all other materials) with all other parameters being constant. Each subject participated in two identical sessions. A repeated-measures analysis of variance was performed to compare the mean response across lens materials/thicknesses and the four curvature values. RESULTS: Significant differences were found only for lens material/thickness (p<0.0001). Although OP-2 and OP-6 (0.53 mm) were manufactured to have the same Dk/t, post hoc comparisons showed that the oxygen uptake rate with OP-6 (0.53 mm) was significantly lower. The same is also true for OP-3 and OP-6 (0.28 mm), with OP-6 (0.28 mm) having a significantly lower oxygen uptake rate. CONCLUSIONS: In contrast to past studies with PMMA, cornea-to-contact lens base curve fitting relationship, with the lens materials and designs studied here, did not affect corneal hypoxic stress, and thick, high Dk lenses resulted in less change in corneal response than did thin, lower Dk lenses of the same Dk/t. This is attributed to the lens reservoir effect that has been previously described.

Adult↗
PubMed2006

Comparison of the experience sampling method and questionnaires to assess visual activities in pre-teen and adolescent children.

AIM: A study was conducted to assess the feasibility of the experience sampling method (ESM) to quantify the daily visual tasks of children. METHODS: Thirty-one children (9-14 years old, 39% male) were randomly paged after school (four times per day) and on weekends (eight times per day) for seven consecutive days. When paged, the children completed a voicemail survey regarding the nature, duration, working distance and type of visual correction worn during the activity. Responses of the subjects were grouped into 14 categories. Before beginning the paging, each child and one parent also reported, via survey, the number of hours and working distance for several visual activities. RESULTS: The usable (complete voicemail responses) response rate was 87.1%. The most commonly reported activity category was watching television (17.8%). Other common responses included distance activities (12.5%), reading/studying (12.2%) and sports/outdoor activities (12.0%). Of the total number of responses, 25% were near work activities (reading/studying, computer use, near hobbies and playing Game Boy). The mean working distance (+/-S.D.) reported was 40.4 +/- 36.9 cm for reading/studying, 232.9 +/- 127.1 cm for watching television, 354.7 +/- 345.8 cm for distance activities and 438.5 +/- 421.0 cm for sports/outdoor activities. When comparing the ESM to surveys, the only significant difference was for the amount of time estimated to be spent in talking/conversation (p < 0.0001). No differences were found for any of the near work activities. CONCLUSIONS: The ESM provides a feasible way to quantify daily near work tasks in children.

Adolescent↗
PubMed2006

Accommodative lag before and after the onset of myopia.

PURPOSE: To evaluate accommodative lag before, during the year of, and after the onset of myopia in children who became myopic, compared with emmetropes. METHODS: The subjects were 568 children who became myopic (at least -0.75 D in each meridian) and 539 children who were emmetropic (between -0.25 D and +1.00 D in each meridian at all visits) participating between 1995 and 2003 in the Collaborative Longitudinal Evaluation of Ethnicity and Refractive Error (CLEERE) Study. Accommodative lag was measured annually with either a Canon R-1 (Canon USA., Lake Success, NY; no longer manufactured) or a Grand Seiko WR 5100-K (Grand Seiko Co., Hiroshima, Japan) autorefractor. Subjects wore their habitual refractive corrections while viewing a letter target accommodative stimulus of 4 D (either in a Badal system or at 25 cm from the subject, designated Badal and near, respectively) or of 2 D (Badal only). Refractive error was measured with the same autorefractor in subjects under cycloplegia. Accommodative lag in children who became myopic was compared to age-, gender-, and ethnicity-matched model estimates of emmetropic values for each annual visit from 5 years before, through 5 years after, the onset of myopia. RESULTS: In the sample as a whole, accommodative lag was not significantly different in children who became myopic compared with model estimates in emmetropes in any year before onset of myopia for either the 4-D or 2-D Badal stimulus. For the 4-D near target, there was only a greater amount of accommodative lag in children who became myopic compared with emmetropes 4 years before onset (difference, 0.22 D; P = 0.0002). Accommodative lag was not significantly elevated during the year of onset of myopia in any of the three measurement conditions (P < 0.82 for all three). A consistently higher lag was seen in children after the onset of their myopia (range, 0.13-0.56 D; P < 0.004 for all comparisons). These patterns were generally followed by each ethnic group, with Asian children typically showing the most, African-American and white children showing the least, and Hispanic children having intermediate accommodative lag. CONCLUSIONS: Substantive and consistent elevations in accommodative lag relative to model estimates of lag in emmetropes did not occur in children who became myopic before the onset of myopia or during the year of onset. Increased accommodative lag occurred in children after the onset of myopia. Elevated accommodative lag is unlikely to be a useful predictive factor for the onset of myopia. Increased hyperopic defocus from accommodative lag may be a consequence rather than a cause of myopia.

Accommodation, Ocular↗
PubMed2005

A randomized clinical trial of treatments for convergence insufficiency in children.

OBJECTIVE: To compare vision therapy/orthoptics, pencil push-ups, and placebo vision therapy/orthoptics as treatments for symptomatic convergence insufficiency in children 9 to 18 years of age. METHODS: In a randomized, multicenter clinical trial, 47 children 9 to 18 years of age with symptomatic convergence insufficiency were randomly assigned to receive 12 weeks of office-based vision therapy/orthoptics, office-based placebo vision therapy/orthoptics, or home-based pencil push-ups therapy. MAIN OUTCOME MEASURES: The primary outcome measure was the symptom score on the Convergence Insufficiency Symptom Survey. Secondary outcome measures were the near point of convergence and positive fusional vergence at near. RESULTS: Symptoms, which were similar in all groups at baseline, were significantly reduced in the vision therapy/orthoptics group (mean symptom score decreased from 32.1 to 9.5) but not in the pencil push-ups (mean symptom score decreased from 29.3 to 25.9) or placebo vision therapy/orthoptics groups (mean symptom score decreased from 30.7 to 24.2). Only patients in the vision therapy/orthoptics group demonstrated both statistically and clinically significant changes in the clinical measures of near point of convergence (from 13.7 cm to 4.5 cm; P < .001) and positive fusional vergence at near (from 12.5 prism diopters to 31.8 prism diopters; P < .001). CONCLUSIONS: In this pilot study, vision therapy/orthoptics was more effective than pencil push-ups or placebo vision therapy/orthoptics in reducing symptoms and improving signs of convergence insufficiency in children 9 to 18 years of age. Neither pencil push-ups nor placebo vision therapy/orthoptics was effective in improving either symptoms or signs associated with convergence insufficiency.

Adolescent↗
PubMed2005

Repeatability of autorefraction and axial length measurements after laser in situ keratomileusis.

PURPOSE: To assess the repeatability and agreement of refractive error measurements and the repeatability of axial length (AL) measurements in patients after laser in situ keratomileusis (LASIK). SETTING: The Ohio State University College of Optometry, Columbus, Ohio, USA. METHODS: Subjective refraction, autorefraction measurements with the Grand Seiko and Humphrey autorefractors, and AL measurements with the IOLMaster were completed for 40 previously myopic LASIK patients under noncycloplegic and cycloplegic conditions on 2 separate occasions. RESULTS: The mean difference between visits for axial length measurements was 0.008 mm +/- 0.04 (SD). The between visits repeatability for all refractive error measurements were <0.75 diopter (D). The mean difference between the subjective refraction and the Humphrey autorefractor for spherical equivalent was statistically significant under noncycloplegic conditions (-0.90 D, P<.0001) and cycloplegic conditions (-2.05 D, P<.0001). The mean difference between subjective refraction and Grand Seiko autorefraction measurements was not significant under noncycloplegic conditions (+0.05 D, 95% limits of agreement [LoA]=-0.99, 1.09; P=.52) conditions but was statistically significant, but not clinically relevant, under cycloplegic conditions (+0.17 D, 95% LoA=-0.73, 1.07; P=.03). CONCLUSIONS: Refractive error measurements after LASIK using the Grand Seiko autorefractor are reliable and agree well with subjective refraction measurements.

Adult↗
PubMed2005

Sensitivity of the National Eye Institute Refractive Error Quality of Life instrument to refractive surgery outcomes.

PURPOSE: To evaluate scores from the National Eye Institute Refractive Error Quality of Life instrument (NEI-RQL) relative to refractive surgery outcomes in myopic patients. SETTING: Large institutional ophthalmic practices. METHODS: Patients seeking refractive surgery (n = 59) self-administered the NEI-RQL before and 6 months after surgery; the comparison group of myopes and emmetropes (n = 72) not seeking refractive surgery also completed the NEI-RQL. Myopic patients seeking refractive surgery had bilateral, same-day laser in situ keratomileusis (LASIK) treatment. Regression analyses were conducted to compare survey scores in the LASIK treatment group before surgery with those in the myopic sample who were not seeking refractive surgery and to compare the survey scores in the post-LASIK treatment group (surgical emmetropes) to those in the naturally emmetropic group. Logistic regression was used to determine NEI-RQL subscales that were related to myopic patients seeking refractive surgery and myopic patients not seeking refractive surgery. RESULTS: Myopes seeking LASIK reported greater expectations for vision improvement (P < .0001), greater activity limitations (P < .0001), suboptimal correction (P = .04), worse appearance (P < .0001), and lower satisfaction (P < .0001) than myopes not seeking refractive surgery. Logistic regression showed that worse self-perceived appearance (odds ratio 20.71), more dissatisfaction with current correction (odds ratio 8.28), and higher expectations for "optimal" correction (odds ratio 6.41) were independently associated with myopes seeking LASIK, while better perceived "clarity of vision" (odds ratio = 0.20) was associated with myopes not seeking surgery. Overall, surgical emmetropes were similar to natural emmetropes in terms of refractive-error-specific quality of life (clarity of vision, near vision, far vision, diurnal fluctuations) and clinical measures of visual function, yet they reported significantly better appearance (P = .02) and greater satisfaction (P < .0001) than natural emmetropes. CONCLUSION: The NEI-RQL demonstrated vision-related quality-of-life differences when comparing patient samples associated with refractive surgery.

Adult↗
PubMed2005

Dynamic visual fields of one-eyed observers.

BACKGROUND: The horizontal binocular visual field can extend to more than 200 degrees, while a monocular field is limited to 160 degrees. Additionally, the nose and other facial structures may block the monocular field further during certain eye movements. The purpose of this study was to compare the monocular against the binocular visual field and determine if head and eye movements can functionally overcome any measured deficit. METHODS: In Experiment 1, visual fields were measured monocularly with a bowl perimeter using 5 fixation positions. Binocular visual fields were calculated by combining the monocular visual field with its mirror image. In Experiment 2, subjects were allowed to make head, eye, and body movements to search for flashing lights 360 degrees around them, spaced every 45 degrees. The numbers of lights identified were compared for the subjects performing monocularly versus binocularly. RESULTS: The size of the overall monocular visual field was found to vary between 48% and 76% of the binocular visual field, depending on eye position. For the flashing light experiment, head and eye movements could not overcome the entire visual-field deficit with monocular viewing. Monocular performance remained 11.4% less than binocular performance. CONCLUSIONS: The visual-field deficit seen with monocular viewing is greatest with nasal fixation, and head and eye movements cannot totally compensate for this deficit when viewing time is limited. Vision standards that require full visual fields in each eye are more appropriate for occupations in which peripheral visual targets must be identified and visual search time is limited.

Adult↗
PubMed2005

The comparison of overnight lens modalities (COLM) study.

PURPOSE: The Comparison of Overnight Lens Modalities (COLM) Study is a controlled, randomized, clinical pilot study to determine the sample size required to perform a multicenter clinical trial comparing Paragon CRT lenses with CIBA Vision Focus NIGHT and DAY 30-day continuous-wear silicone hydrogel lenses. METHODS: Twenty subjects were enrolled in the study. Eighteen subjects, 8 CRT and 10 Focus NIGHT and DAY lens wearers, completed the 3-month study. Visual acuity and refractive quality of life were assessed. Nonparametric statistics were used to analyze differences within and between treatment groups for refraction, visual acuity, and refractive quality of life. The Wilcoxon rank sum test was used to analyze differences between the groups in refraction, visual acuity, and refractive quality of life. The Wilcoxon signed rank test was also used to monitor changes in refraction, refractive quality of life, and visual acuity within a group. Sample size calculations were performed to determine the sample size needed for a large-scale clinical trial. RESULTS: No statistically significant difference was observed between the groups for 12 of 13 scales on the National Eye Institute Refractive Error Quality of Life Instrument (NEI RQL-42) after treatment. A statistically significant difference was observed between the CRT and Focus NIGHT and DAY groups after 3 months for the NEI RQL-42 dependence-on-correction scale (P=0.0032). There was a significant change within the CRT group between baseline and 3 months (P=0.0156). No statistically significant difference was observed between the two groups in Bailey-Lovie high- and low-contrast visual acuity after 3 months. CONCLUSIONS: The NEI RQL-42 may be able to detect differences in refractive quality of life between two contact lens treatment groups for the dependence-on-correction scale. Paragon CRT and CIBA Vision Focus NIGHT and DAY lenses produced similar high- and low-contrast visual acuity in this study. A sample size of 126 subjects per group is required to find a 10-unit difference on the NEI RQL-42.

Adult↗
PubMed2005

Personality in keratoconus in a sample of patients derived from the internet.

PURPOSE: Keratoconus is a corneal disease that manifests itself in young adulthood and decreases vision. Anecdotally, keratoconus patients are commonly described as having unusual personality characteristics; however, previous researchers have not been able to define a unique keratoconus personality profile. We sought to better define the personality of patients with keratoconus. METHODS: The Millon Behavioral Health Inventory (MBHI) is a psychological instrument designed for use with physically ill patients to assess factors relevant to their medical care. The MBHI may aid in the evaluation of keratoconus patients and provide information relevant to the doctor-patient relationship. Patients with keratoconus were recruited through the World Wide Web. Surveys were conducted by mail, with all responses returned anonymously. One hundred fifty-three keratoconus patients were compared with the MBHI age-matched norms, generated from medical and nonmedical samples of adults. Subgroups of keratoconus patients were compared based on their self-reported rating of the daily burden of keratoconus. RESULTS: Keratoconus patients scored significantly lower (chi, P <0.05) compared with the normative population on the respectful coping style scale, and their scores were not significantly associated with a history of penetrating keratoplasty or their rating of the effect of keratoconus on their lives. This suggests that keratoconus patients are less respectful of practitioners, uncooperative, and noncompliant with treatment plans. Practitioners may look unfavorably on patients who exhibit these characteristics. This would also explain why the clinical perception of keratoconus patients persists, but other personality inventories have not defined a distinct keratoconus profile. CONCLUSIONS: These data from the MBHI, showing that keratoconus patients score lower on the respectful coping style scale, may explain eye care practitioners' perceptions about these patients' personality characteristics.

Adolescent↗
PubMed2005

An assessment of grading scales for meibography images.

PURPOSE: To evaluate the within- and between-reader reliability and the interrelation between 2 methods of grading meibography images. METHODS: A video meibography sequence (1200 frames) was captured from 290 patients using near-infrared light (650-700 nm) and a near-infrared CCD camera. One frame was selected for grading by 2 masked readers using 2 scales, where the first reader graded the image on 2 occasions and the second reader graded the image on 1 occasion. The first grading scale was a gestalt assessment (categorically graded), which is an assessment of partial meibomian glands within the image. The second was a count of individual whole glands. Within- and between-reader reliability and concurrent validity between the scales were examined. RESULTS: Within-reader reliability of the gestalt scale was moderate to high (simple kappa = 0.78, 95% confidence interval [CI] = 0.71-0.85 and weighted kappa = 0.91, 95% CI = 0.88-0.95). Within-reader reliability of individual gland counting was moderate via a 95% limits of agreement analysis (-2.84-2.76 glands). Between-reader reliability of the gestalt scale was fair (simple kappa = 0.38, 95% CI = 0.30-0.46 and weighted kappa = 0.57, 95% CI = 0.47-0.68). Between-reader reliability of gland counting was fair via a 95% limits of agreement analysis (-4.46-5.08 glands). There was a strong relation between the gestalt scale and gland counting indicating good concurrent validity (Z = -15.15, P < 0.0001). CONCLUSIONS: These methods of grading meibography images demonstrate good within-reader reliability and fair between-reader reliability. Responsiveness to change will need to be addressed in future studies.

Adult↗
PubMed2005

The impact of contact lens care solutions on the thickness of the tear film and contact lens.

PURPOSE: To determine the impact of compositional differences in contact lens care solutions on the thickness of the tear film during contact lens wear. METHODS: A randomized, crossover, investigator-masked clinical trial was conducted to compare AMO's Complete MoisturePlus to Alcon's Opti-Free Express in 31 subjects. The primary outcome of this study was a comparison of prelens tear film (PLTF) and postlens tear film (PoLTF) thickness values obtained during the first 2 hours of etafilcon A hydrogel lens wear. Each solution was used by each participant for a period of 7 days, separated by a washout period of 1 day. Alternative outcomes studied included prelens tear film thinning rates, solution preference, and dry eye-related symptom scores. Tear film thickness measurements were made using a noninvasive wavelength-dependent interferometric system. RESULTS: The average overall PLTF thickness over the 120-minute time period after using Complete MoisturePlus was 3.02 +/- 1.07 microm, whereas the average overall PLTF thickness in this same time interval after using Opti-Free Express was 2.72 +/- 0.86 (P = 0.003). For both solutions, the PLTF could be fitted by the sum of an exponential decay plus a constant. The PLTF decay amplitudes did not statistically differ when the solutions were compared (P = 0.11). There was no difference in overall PoLTF thicknesses when the average values after using each solution were compared (P = 0.57), although there was a difference immediately after the lens was applied to the eye (Complete MoisturePlus average = 4.10 versus Opti-Free Express average = 3.48, P = 0.02). The PoLTF also demonstrated an exponential decay for both solutions. The PoLTF decay amplitudes did not statistically differ (P = 0.14). Twenty subjects (64.5%) preferred Complete MoisturePlus to Opti-Free Express (35.5%) (P = 0.11), and nearly every subject (90.3%) suggested "comfort" as their reason for preference. CONCLUSIONS: Complete MoisturePlus is associated with a thicker PLTF when compared with Opti-Free Express in contact lens wearers without dry eye symptoms, especially during the first 5 minutes following lens insertion.

Adult↗