The Dundee University Scottish Keratoconus study: demographics, corneal signs, associated diseases, and eye rubbing.

AIM: To investigate and correlate the corneal, refractive, topographic and familial characteristics of a large cohort with keratoconus. METHODS: Prospective observational study of 200 consecutive patients presenting with keratoconus during the 4 year-period 1997-2000. Subjects were examined at enrolment and at a final review. Data were collected on demographic characteristics, referral route, symptoms, refractive correction, eye rubbing, family history, medical history, slit-lamp biomicroscopic corneal signs, and computerized corneal topography. RESULTS: Mean age at enrolment was 30.9+/-10.4 (range, 12.2-72) years (N=200, 62.5% male, 93% white Caucasian) with a 5% family history of keratoconus. Atopic diseases included asthma (23%), eczema (14%), and hay fever (30%). Only 9% wore contact lenses before referral. Mean follow-up was 1004 days +/-282 (range, 390-1335) and 9.7+/-8.9 (range, 1.1-60) years from diagnosis. The mean simulated K1 corneal power at enrolment was 51.74+/-5.36 (range, 42.59-67.32) D and 88.5% exhibited bilateral keratoconus. Fifty-three (15%) topographically confirmed cones exhibited no clinical corneal signs at presentation. At enrollment, 56% had a pachymetry <0.480 mm increasing to 77% at final review. Forty-eight percent of subjects reported significant eye rubbing and there was a highly statistically significant difference (two sample t-test P=0.018) between keratoconus and control groups. TMS-2 axial corneal power was strongly associated with corneal scarring and age at diagnosis. The size of the scarring effect was 2.2 D (95% confidence interval (CI) 1.34, 3.06). CONCLUSIONS: This study provides an overview of a large population with keratoconus highlighting presenting features and clinical and topographic progression over a 4 year-period.

The Dundee University Scottish Keratoconus Study II: a prospective study of optical and surgical correction.

AIM: To investigate and correlate optical correction, and progression to penetrating keratoplasty (PKP), with the corneal, refractive, topographic and familial characteristics of subjects with keratoconus, within the Tayside region of Scotland. METHOD: Prospective, observational, longitudinal study design. Two hundred subjects with keratoconus were enrolled into the Dundee University Scottish Keratoconus Study (DUSKS) and were assessed during a 4-year period using standardised clinical assessment, computerised corneal topography and questionnaires. RESULTS: Keratoconic subjects in this study wore rigid contact lenses (90.6%) for longer than 12 hours per day (81%), 7 days a week (91%) and achieved a very good level of Snellen visual acuity (97%, > or =6/9). Corneal staining was observed in the majority of corneas (71%), although only a small percentage of subjects reported major problems of: discomfort (18%), hyperaemia (16%), or the lens falling out (4%). Poor visual acuity was the main reason (79%) for undergoing PKP usually in the latter part of the third decade of life, approximately a decade after diagnosis. During the study period 4% of eyes progressed to PKP. Only a small percentage of eyes (9.5%) required no visual correction postoperatively. CONCLUSION: The main mode of visual rehabilitation for keratoconus was rigid contact lenses, which were mostly worn successfully with good visual acuity. During the study period a small minority of keratoconics progressed to corneal graft surgery. It is advisable to emphasise that postoperatively refractive correction will be required in the majority of these cases.

Quantitative analysis of corneal microstructure in keratoconus utilising in vivo confocal microscopy.

PURPOSE: To establish and quantify the in vivo confocal microscopic features of moderate to advanced keratoconus. METHODS: Nineteen keratoconus subjects were catergorised using Orbscan-derived corneal apex power and pachymetry as exhibiting moderate (n=7) and advanced (n=12) keratoconus. Control subjects included 23 noncontact lens wearers (Group A) and 15 contact lens wearers (Group B). All subjects underwent Confoscan slit scanning in vivo confocal microscopy. RESULTS: Compared with Group A (4912+/-434 cells/mm(2)), basal epithelial density was significantly lower in both moderate (4592+/-414 cells/mm(2), P<0.05) and advanced keratoconus (4530+/-596 cells/mm(2), P=0.01). In comparison to Group A (761+/-118 cells/mm(2)), anterior stroma keratocyte density was significantly greater in both moderate keratoconus (883+/-111 cells/mm(2), P=0.001) and advanced keratoconus (952+/-122 cells/mm(2), P<0.001). Compared to Group A (504+/-80 cells/mm(2)) posterior stroma keratocyte density was also significantly greater in advanced keratoconus (599+/-97 cells/mm(2), P<0.001) and posterior stromal keratocyte density appeared to increase with increasing severity of keratoconus (P<0.05). However, comparing control Groups A and B, contact lens wear per se, was associated with significantly reduced (P=0.000) keratocyte density in the anterior stroma (609+/-66 cells/mm(2)) and demonstrated a trend (P=0.056) in the posterior stroma (470+/-63 cells/mm(2)). Keratoconic corneas (429+/-72 microm) were significantly thinner than control Groups A (508+/-77 mm) and B (495+/-80 microm). The presence of keratoconus did not affect the endothelial cell density (P=0.54). CONCLUSION: In vivo confocal microscopy can provide insight into the microstructural changes that occur in keratoconus.

The variable expression of keratoconus within monozygotic twins: dundee University Scottish Keratoconus Study (DUSKS).

INTRODUCTION: As part of a longitudinal observational prospective study (Dundee University Scottish Keratoconus Study, DUSKS) a caucasian female subject was identified with keratoconus affecting both corneas. Of interest was that the subject's mother was a monozygotic twin, however, the mother was reportedly unaffected by keratoconus, although her sister (the subject's aunt) had been diagnosed with keratoconus. METHOD: Computer video-keratoscopy (CVK) was undertaken was on this family to clarify this apparent discordance. RESULTS: CVK demonstrated the variable expression of the keratoconic phenotype, by identifying evidence of subclinical keratoconus in the 'unaffected' twin. CONCLUSION: So far only one set of monozygotic twins with keratoconus have been reported within the UK, this paper reports a second. Since CVK has been available the majority agree on concordance of keratoconus expression but not all, including this study. If monozygotic twin studies demonstrate heterogeneity of keratoconus this may at least explain the contradictory data that exists within the literature and why the inheritance pattern of keratoconus is still unclear in 2005.

Atypical unilateral superior keratoconus in young males.

Generally in keratoconus the corneal apex displacement is inferior in position and bilateral in expression. Two young male keratoconic subjects enrolled in the Dundee University Scottish Keratoconus Study (DUSKS) demonstrated with corneal topography the presence of unilateral superior keratoconus. Successful visual rehabilitation of a superior cone with contact lens fitting represents a particular challenge to the contact lens practitioner. This report discusses the management of two such cases.

Safety and predictability of laser in situ keratomileusis enhancement by flap reelevation in high myopia.

PURPOSE: To evaluate the safety and predictability of laser in situ keratomileusis (LASIK) retreatment following primary procedures for high myopia and astigmatism. SETTING: Corneal Diseases and Excimer Laser Research Unit, Department of Ophthalmology, University of Dundee, Dundee, United Kingdom. METHODS: This prospective observational study of retreatment comprised a cohort of 109 eyes having primary LASIK for high myopia and astigmatism with a spherical equivalent (SE) of -9.70 diopters (D) +/- 4.06 (SD). Twenty-four eyes (22%) with an initial myopic SE of -9.83 +/- 3.50 D, a comparable subset of the entire group (P < .05), had retreatment for residual myopia (-3.02 +/- 2.17 D) to improve uncorrected visual acuity (UCVA) by reelevating the corneal flap and ablating the stromal bed. RESULTS: The mean follow-up after retreatment was 12.8 +/- 5.1 months (range 1.5 to 24 months; 19 eyes >/=6 months, 13 eyes > or = 12 months). The mean myopic SE was reduced to +0.53 +/- 0.62 D at 1 week, +0.05 +/- 0.50 D at 1 month, +0.30 +/- 0.50 D at 6 months, and +0.18 +/- 0.42 D at the latest follow-up, 12.8 months. At the latest review, 62% of eyes were within +/-0.50 D of emmetropia and 100% were within +/-1.00 D. The mean refraction did not alter statistically between 1 week and subsequent times. The mean UCVA improved from 6/30 prior to retreatment to 6/9 at the latest follow-up. Uncorrected visual acuity of 6/6 or better, 6/9 or better, and 6/12 or better was achieved by 33.0%, 75.0%, and 95.8% of eyes, respectively. No significant complications that led to a loss of best corrected visual acuity were encountered, although retreatment procedures were more uncomfortable than primary procedures and self-limiting; epithelial ingrowth that did not threaten vision was common, and 2 patients complained of nighttime visual symptoms. CONCLUSIONS: Retreatment of residual myopia by reelevating the flap was relatively safe and predictable, with a low risk of sight-threatening complications. However, longer term studies may be required to detect late complications.

Prenatal maternal predictors of cognitive and emotional delays in children of adolescent mothers.

The present study examined relationships among prenatal characteristics of 121 adolescent mothers-including cognitive readiness for parenting, intelligence, social support, and personal adjustment-and intellectual-linguistic development, social-emotional functioning, and adaptive behavior in their children at three years of age. Only 28% of the children scored within normal ranges on all three types of outcomes. Intellectual and linguistic delays were predicted best by prenatal measures of maternal Performance IQ and social support from extended family. Socioemotional problems were predicted best by maternal internalizing problems and social support from partner and friends. Adaptive behavior was associated with parenting style. Implications for the early identification of high-risk children--and associated intervention programs--are discussed.

Laser in situ keratomileusis for ametropia after penetrating keratoplasty.

PURPOSE: To evaluate the efficacy of excimer laser in situ keratomileusis (LASIK) in the treatment of refractive errors after penetrating keratoplasty. METHODS: Eight eyes underwent LASIK after a mean 71 months (SD 60) following the initial penetrating keratoplasty. A full ophthalmic assessment was performed before LASIK and at 1 week, 1, 3, 6, and 12 months after surgery. Mean follow-up was 8.6 months (SD 3.2). RESULTS: No eyes lost any Snellen lines of best spectacle-corrected visual acuity at the latest follow-up. Mean reduction in spherical equivalent refraction was 91% from -6.79 D (SD 4.17) to -0.64 D (SD 1.92) and mean reduction of cylinder was 72% from -6.79 D (SD 3.28) to -1.93 D (SD 1.17) at 6 months. Mean surgically induced astigmatism was 5.50 D (SD 2.42) and the index of surgically induced astigmatism divided by the initial cylinder expressed as a percentage was 81%. Mean outcome indices were: correction index 0.87, index of success 0.31, and angle of error 0.95 degrees. Three eyes (43%) achieved a spherical equivalent refraction of +/-0.50 D and 4 eyes (57%) achieved a spherical equivalent refraction of +/-1.00 D of emmetropia. CONCLUSIONS: The efficacy of LASIK after penetrating keratoplasty was good compared to incisional or surface based excimer laser methods and has the advantage of reducing the myopic spherical equivalent refraction in addition to astigmatism, thus improving the uncorrected visual acuities.

Functional, psychological, and satisfaction outcomes of laser in situ keratomileusis for high myopia.

PURPOSE: To identify factors that motivate patients to seek laser in situ keratomileusis (LASIK) treatment for myopia and establish subjective levels of functional improvement and satisfaction across a range of indices after LASIK surgery. SETTING: The Corneal Diseases and Excimer Laser Research Unit, University of Dundee, Ninewells Hospital and Medical School, Dundee, Scotland. METHODS: In this questionnaire-based, cross-sectional study, an anonymous 34-item questionnaire was forwarded to 50 consecutive patients in a prospective study who had had LASIK for high myopia by a single surgeon at a single center. The questionnaire used visual analog scales, anchored at each end by an adjectival descriptor. The mean preoperative myopia was -10.7 diopters +/- 4.4 (SD). Seventy-six percent of eyes (83% of patients) achieved post-LASIK uncorrected visual acuity (UCVA) of 6/12 or better; 1 eye lost 2 lines of corrected Snellen visual acuity. RESULTS: A 98% reply rate was achieved. The most common motivating factor for pursuing LASIK was to improve UCVA (88%); only 21% rated improved cosmesis as an important motive. Most patients (81% to 100%) reported functional improvement across the spectrum of visual tasks assessed, although 8.8% reported difficulty with nighttime driving. Ninety-six percent felt their UCVA was as good as anticipated, 97.9% were satisfied with the speed of visual improvement, 93.8% achieved the goals for which they had surgery, 97.9% reported an improved quality of life, and 97.9% were satisfied with the overall outcome of LASIK. CONCLUSIONS: Using an anonymous, wide-ranging questionnaire, high levels of functional improvement and satisfaction with the speed of visual recovery and outcome were reported by patients after LASIK for high myopia. Nighttime driving symptoms of variable severity were, however, noted by 8.8% of patients, despite high levels of satisfaction with other aspects of visual function.

Referral patterns, treatment management and visual outcome in keratoconus.

PURPOSE/METHOD: To determine the patterns of referral, the hospital-based management and the subjective degree of visual success achieved by keratoconics attending the Corneal Service at Sunderland Eye Infirmary, England, a specifically designed anonymous questionnaire was mailed to 160 keratoconus subjects. RESULTS: The following responses were obtained from 97 (61%) respondents: mean age of first referral (22.88 +/- 8.36 years); gender (male:female ratio 3:1); source of initial referral (optometrists 90%); visual symptoms experienced before referral (46% complained of blurred/distorted vision); and the type of visual correction before referral (70% wore a refractive correction: 72% spectacles, 28% contact lenses). Initial post-referral treatment included bilateral contact lens fitting (65%), monocular contact lens correction (26%), penetrating keratoplasty (8%) and no intervention (1%). Two-thirds of subjects were presently wearing contact lenses (67%), with the mean period of successful lens wear being 8.26 +/- 7.92 years, and 31% had undergone penetrating keratoplasty (PK) since initial referral. A subjective evaluation of visual acuity with contact lenses was made by respondents using a visual analogue scale. The mean value was 86.86 +/- 15.25 (range 50-100 mm), with 50 mm representing moderate visual acuity. Of those who underwent PK the mean subjective evaluation of the change in post-operative vision compared with pre-operatively was 82.41 +/- 26.57 (range 1-100 mm), with 50 mm representing no visual change. The majority of subjects therefore noted a moderate to marked visual improvement following PK. CONCLUSION: In this fairly young group of patients, predominantly male, the majority wore a refractive correction for approximately 10 years before referral to the Hospital Eye Service (HES). Most referrals were initiated by optometrists. On initial HES assessment the treatment for two-thirds was bilateral contact lens fitting; only a quarter were fitted monocularly. However, by the time of this study only a tenth retained monocular contact lens correction, with the mean length of time from diagnosis to bilateral contact lens wearing being approximately 5 1/2 years. The progressive nature of this disease is further evidenced by the large number of contact lens sets required by patients (approximately 5) and by the number of patients (n = 22) requiring PK, the mean length of time from diagnosis to corneal graft being approximately 8 1/2 years.

Fourier analysis of corneal topography data after photorefractive keratectomy.

PURPOSE: To evaluate the relation between measures of corneal power and refractive error after photorefractive keratectomy (PRK) by applying fast Fourier transform (FFT) to computerized corneal topography data. SETTING: Corneal Diseases and Excimer Laser Clinic, Sunderland Eye Infirmary, Sunderland, England, and University of Dundee Department of Ophthalmology, Dundee, Scotland. METHODS: Twenty-six left eyes of consecutive patients treated by PRK with a VISX Twenty-Twenty excimer laser were retrospectively analyzed. Preoperative and 3, 6, and 12 month postoperative data were studied. Changes in corneal parameters derived from corneal topography data using the FFT were compared with changes in refractive status vectors (spherical equivalent and astigmatic cosine and sine values). RESULTS: Although highly correlated (r2 = 0.8839), the change in FFT-derived corneal spherical equivalent underestimated the change in refractive spherical equivalent by 25.5% over the 12 month follow-up. Decentration, measured by the 1-cycle FFT harmonic, increased significantly from a mean preoperative value of 0.12 mm +/- 0.07 (SD) to 0.51 +/- 0.35 mm 12 months postoperatively. CONCLUSIONS: The FFT is a powerful method for extracting clinically meaningful descriptors from corneal topography data; however, care must be taken when interpreting refractive changes from corneal data.

Ocular and subjective responses to frequent replacement of daily wear soft contact lenses.

PURPOSE: A significant number of soft contact lens wearers develop complications as a result of lens contamination. We conducted a single-blind 2 year clinical trial to determine if scheduled frequent replacement of lenses decreases complications. METHODS: One hundred nineteen non-contact lens wearers were fit with soft contact lenses and randomly assigned to 1 or 3 month replacement schedules or a non-replacement (control) group. All subjects were fit with 0.04 mm thick HEMA (water content: 38%) lenses to be worn on a daily wear basis only. A single multipurpose solution was prescribed for cleaning and disinfection. RESULTS: The 2-year results showed a significantly greater number of subjects in the non-replacement group exhibited microcysts, infiltrates, clinically significant corneal staining, and limbal and bulbar injection. As a result of lens deposition and damage, approximately twice the number of unscheduled lens replacements per subject were necessary in the non-replacement group compared with the 1 and 3 month replacement groups. Overall subject satisfaction with lens wear decreased in the non-replacement group and increased in the 1 and 3 month replacement groups over the 2-year period. CONCLUSIONS: Frequent replacement of soft lenses for daily wear as compared to non-replacement daily wear: 1) is less likely to cause contact lens induced complications; 2) reduces the number of unscheduled lens replacements; and 3) improves satisfaction with lens wear.

Hazy days? The refractive outlook of photo-refractive keratectomy/photo-astigmatic keratectomy.

The refractive outcome of 100 healthy myopic eyes which had undergone excimer laser (VISX 20/20) was evaluated at 6 months post-treatment. Patients were subdivided into Group A (n = 51, < -5.00 D spherical equivalent (SE)), Group B (n = 38, -5.00 to < -10.00 D SE) and Group C (n = 11, > -10.00 D SE). The mean myopic sphere decreased from -2.88 to -0.22 DS, -5.94 to -0.43 DS and -12.61 to -1.83 DS, respectively. Cylinder reduction ranged from 23 to 53%, effectiveness: decreasing with increasing associated myopia. Sixty-six percent of all subjects attained an SE correction within 1.00 D of that attempted, however, 80% actually achieved vision of 6/12 or better. At 6 months only six eyes were not within one line of their pre-operative best spectacle visual acuity (BSVA) and four of these exhibited haze greater than Grade 1. In low myopia, photorefractive keratectomy (PRK) appears to be highly successful with 93% of subjects with an initial myopia of < -5.00 D SE obtaining 6/12 or better vision. However, photo-astigmatic refractive keratectomy (PARK) was variable within all groups.

The effectiveness of imagery and sentence strategy instructions as a function of visual and auditory processing in young school-age children.

The relationship between auditory and visual processing modality and strategy instructions was examined in first- and second-grade children. A Pictograph Sentence Memory Test was used to determine dominant processing modality as well as to assess instructional effects. The pictograph task was given first followed by auditory or visual interference. Children who were disrupted more by visual interference were classed as visual processors and those more disrupted by auditory interference were classed as auditory processors. Auditory and visual processors were then assigned to one of three conditions: interactive imagery strategy, sentence strategy, or a control group. Children in the imagery and sentence strategy groups were briefly taught to integrate the pictographs in order to remember them better. The sentence strategy was found to be effective for both auditory and visual processors, whereas the interactive imagery strategy was effective only for auditory processors.