Visual function correlates of self-reported vision-related nighttime driving difficulties / La función visual se correlaciona con las dificultades de conducción nocturna relacionadas con la visión autoinformadas

Purpose: To investigate the visual function correlates of self-reported vision-related night driving difficulties among drivers. Methods: One hundred and seven drivers (age: 46.06 ± 8.24, visual acuity [VA] of 0.2logMAR or better) were included in the study. A standard vision and night driving questionnaire (VND-Q) was administered. VA and contrast sensitivity were measured under photopic and mesopic conditions. Mesopic VA was remeasured after introducing a peripheral glare source into the participants' field of view to enable computation of disability glare index. Regression analyses were used to assess the associations between VND-Q scores, and visual function measures. Results: The mean VND-Q score was -3.96±1.95 logit (interval scale score: 2.46±1.28). Simple linear regression models for photopic contrast sensitivity, mesopic VA, mesopic contrast sensitivity, and disability index significantly predicted VND-Q score (P<0.05), with mesopic VA and disability glare index accounting for the greatest variation (21 %) in VND-Q scores followed by photopic contrast sensitivity (19 %), and mesopic contrast sensitivity (15 %). A multiple regression model to determine the association between the predictors (photopic contrast sensitivity, mesopic VA, mesopic contrast sensitivity, and disability index) and VND-Q score yielded significant results, F (4, 102) = 8.58, P < 0.001, adj. R2 = 0.2224. Seeing dark-colored cars was the most challenging vision task. Conclusion: Changes in mesopic visual acuity, photopic and mesopic contrast sensitivity, as well as disability glare index are associated with and explain night driving-related visual difficulties. It is recommended to incorporate measurement of these visual functions into assessments related to driving performance.(AU)

Effect of the chromaticity of stimuli on night vision disturbances.

The perception of halos and other night vision disturbances is a common complaint in clinical practice. Such visual disturbances must be assessed in order to fully characterize each patient's visual performance, which is particularly relevant when carrying out a range of daily tasks. Visual problems are usually assessed using achromatic stimuli, yet the stimuli encountered in daily life have very different chromaticities. Hence, it is important to assess the effect of the chromaticity of visual stimuli on night vision disturbances. The aim of this work is to study the influence of the chromaticity of different visual stimuli on night vision disturbances by analyzing straylight and visual discrimination under low-light conditions. For that, we assessed the monocular and binocular visual discrimination of 27 subjects under low illumination using the Halo test. The subjects' visual discrimination was assessed after exposure to different visual stimuli: achromatic, red, green, and blue, both at the monitor's maximum luminance and maintaining the same luminance value for the different visual stimuli. Monocular straylight was also measured for an achromatic, red, green, and blue stimuli. The blue stimulus had the greatest effect on halos in both monocular and binocular conditions. Visual discrimination was similar for the red, green, and achromatic stimuli, but worsened at lower luminance. The greatest influence of straylight was observed for the blue stimulus. In addition, visual discrimination correlated with straylight measurements for achromatic stimuli, wherein greater straylight values correlated with an increased perception of halos and other visual disturbances.

Spatially Resolved Association of Structural Biomarkers on Retinal Function in Non-Exudative Age-Related Macular Degeneration Over 4 Years.

Purpose: To longitudinally assess the impact of high-risk structural biomarkers for natural disease progression in non-exudative age-related macular degeneration (AMD) on spatially resolved mesopic and scotopic fundus-controlled perimetry testing. Methods: Multimodal retinal imaging data and fundus-controlled perimetry stimuli points were semiautomatically registered according to landmark correspondences at each annual visit over a period of up to 4 years. The presence of sub-RPE drusen, subretinal drusenoid deposits, pigment epithelium detachments (PEDs), hyper-reflective foci (HRF), vitelliform lesions, refractile deposits, and incomplete RPE and outer retinal atrophy (iRORA) and complete RPE and outer retinal atrophy (cRORA) were graded at each stimulus position and visit. Localized retinal layer thicknesses were extracted. Mixed-effect models were used for structure-function correlation. Results: Fifty-four eyes of 49 patients with non-exudative AMD (mean age, 70.7 ± 9.1 years) and 27 eyes of 27 healthy controls (mean age, 63.4 ± 8.9 years) were included. During study course, presence of PED had the highest functional impact with a mean estimated loss of -1.30 dB (P < 0.001) for mesopic and -1.23 dB (P < 0.001) for scotopic testing, followed by HRF with -0.89 dB (mesopic, P = 0.001) and -0.87 dB (scotopic, P = 0.005). Subretinal drusenoid deposits were associated with a stronger visual impairment (mesopic, -0.38 dB; P = 0.128; scotopic, -0.37 dB; P = 0.172) compared with sub-RPE drusen (-0.22 dB, P = 0.0004; -0.18 dB, P = 0.006). With development of c-RORA, scotopic retinal sensitivity further significantly decreased (-2.15 dB; P = 0.02). Thickening of the RPE-drusen-complex and thinning of the outer nuclear layer negatively impacted spatially resolved retinal sensitivity. Conclusions: The presence of PED and HRF had the greatest prognostic impact on progressive point-wise sensitivity losses. Higher predominant rod than cone-mediated localized retinal sensitivity losses with early signs of retinal atrophy development indicate photoreceptor preservation as a potential therapeutic target for future interventional AMD trials.

The role of visual conditions and aircraft type on different aspects of pilot workload.

OBJECTIVE: The objective of our work was to assess the impact of flight conditions by aircraft type on the workload estimated using NASA-Task Load Index (NASA-TLX). BACKGROUND: Learning about subjective workload is important for assessing the impact of a pilot's work environment on their performance in the cockpit. This is an important element of flight safety and includes the prevention of aviation accidents. METHODS: The study included 146 military pilots that fly the following aircrafts: flying fast-jet (21), fixed-wing (24), and rotary-wing (101). The NASA-TLX questionnaire was used to assess workload and pilots were asked to determine the level of workload resulting from flying under the following conditions: daytime flight (VFR), night-vision flight performed under Night Visual Flight Rules (NVFR), and night-vision flight using night-vision goggles (NVGs). RESULTS: The highest level of workload was consistently attributed to flights performed under NVG conditions. NVFR conditions were rated as the most burdensome, while VFR conditions were rated as the least burdensome. Fast-jet pilots rated their mental performance and effort workload as significantly higher than pilots of other aircrafts. CONCLUSION: Pilots' perceived workload is influenced by both flight conditions and the type of aircraft they fly. Workload knowledge is important for flight safety and should be taken into account during training and flight-task planning. APPLICATION: The results of our study can be useful both in flight training and in work on the effectiveness of the human-machine interface. Awareness of one's own limitations due to the work environment can help improve flight safety.

Retinal sensitivity changes in early/intermediate AMD: a systematic review and meta-analysis of visual field testing under mesopic and scotopic lighting.

Visual fields under mesopic and scotopic lighting are increasingly being used for macular functional assessment. This review evaluates its statistical significance and clinical relevance, and the optimal testing protocol for early/intermediate age-related macular degeneration (AMD). PubMed and Embase were searched from inception to 14/05/2022. All quality assessments were performed according to GRADE guidelines. The primary outcome was global mean sensitivity (MS), further meta-analysed by: AMD classification scheme, device, test pattern, mesopic/scotopic lighting, stimuli size/chromaticity, pupil dilation, testing radius (area), background luminance, adaptation time, AMD severity, reticular pseudodrusen presence, and follow-up visit. From 1489 studies screened, 42 observational study results contributed to the primary meta-analysis. Supported by moderate GRADE certainty of the evidence, global MS was significantly reduced across all devices under mesopic and scotopic lighting with large effect size (-0.9 [-1.04, -0.75] Hedge's g, P < 0.0001). The device (P < 0.01) and lighting (P < 0.05) used were the only modifiable factors affecting global MS, whereby the mesopic MP-1 and MAIA produced the largest effect sizes and exceeded test-retest variabilities. Global MS was significantly affected by AMD severity (intermediate versus early AMD; -0.58 [-0.88, -0.29] Hedge's g or -2.55 [3.62, -1.47] MAIA-dB) and at follow-up visit (versus baseline; -0.62 [-0.84, -0.41] Hedge's g or -1.61[-2.69, -0.54] MAIA-dB). Magnitudes of retinal sensitivity changes in early/intermediate AMD are clinically relevant for the MP-1 and MAIA devices under mesopic lighting within the central 10° radius. Other factors including pupil dilation and dark adaptation did not significantly affect global MS in early/intermediate AMD.

Convergent mechanism underlying the acquisition of vertebrate scotopic vision.

High sensitivity of scotopic vision (vision in dim light conditions) is achieved by the rods' low background noise, which is attributed to a much lower thermal activation rate (kth) of rhodopsin compared with cone pigments. Frogs and nocturnal geckos uniquely possess atypical rods containing noncanonical cone pigments that exhibit low kth, mimicking rhodopsin. Here, we investigated the convergent mechanism underlying the low kth of rhodopsins and noncanonical cone pigments. Our biochemical analysis revealed that the kth of canonical cone pigments depends on their absorption maximum (λmax). However, rhodopsin and noncanonical cone pigments showed a substantially lower kth than predicted from the λmax dependency. Given that the λmax is inversely proportional to the activation energy of the pigments in the Hinshelwood distribution-based model, our findings suggest that rhodopsin and noncanonical cone pigments have convergently acquired low frequency of spontaneous-activation attempts, including thermal fluctuations of the protein moiety, in the molecular evolutionary processes from canonical cone pigments, which contributes to highly sensitive scotopic vision.

Visual function correlates of self-reported vision-related nighttime driving difficulties.

PURPOSE: To investigate the visual function correlates of self-reported vision-related night driving difficulties among drivers. METHODS: One hundred and seven drivers (age: 46.06 ± 8.24, visual acuity [VA] of 0.2logMAR or better) were included in the study. A standard vision and night driving questionnaire (VND-Q) was administered. VA and contrast sensitivity were measured under photopic and mesopic conditions. Mesopic VA was remeasured after introducing a peripheral glare source into the participants' field of view to enable computation of disability glare index. Regression analyses were used to assess the associations between VND-Q scores, and visual function measures. RESULTS: The mean VND-Q score was -3.96±1.95 logit (interval scale score: 2.46±1.28). Simple linear regression models for photopic contrast sensitivity, mesopic VA, mesopic contrast sensitivity, and disability index significantly predicted VND-Q score (P<0.05), with mesopic VA and disability glare index accounting for the greatest variation (21 %) in VND-Q scores followed by photopic contrast sensitivity (19 %), and mesopic contrast sensitivity (15 %). A multiple regression model to determine the association between the predictors (photopic contrast sensitivity, mesopic VA, mesopic contrast sensitivity, and disability index) and VND-Q score yielded significant results, F (4, 102) = 8.58, P < 0.001, adj. R2 = 0.2224. Seeing dark-colored cars was the most challenging vision task. CONCLUSION: Changes in mesopic visual acuity, photopic and mesopic contrast sensitivity, as well as disability glare index are associated with and explain night driving-related visual difficulties. It is recommended to incorporate measurement of these visual functions into assessments related to driving performance.

Irlen syndrome: systematic review and level of evidence analysis / Síndrome de Irlen: revisão sistemática e análise do nível de evidência

ABSTRACT Background: Scotopic sensitivity syndrome, later called Meares-Irlen syndrome or simply Irlen syndrome (IS) has been described as symptoms of poor reading ability due to poor color matching and distorted graphic images. Individuals with this syndrome are considered slow, ineffective readers with low comprehension and visual fatigue. It is still uncertain whether the disease pathophysiology is an independent entity or part of the dyslexia spectrum. Nevertheless, treatments with lenses and colored filters have been proposed to alleviate the effect of the luminous contrast and improve patients' reading performance. However, no evidence of treatment effectiveness has been achieved. Objective: The aim of the present study was to obtain evidence about IS etiology, diagnosis and intervention efficacy. Methods: A systematic review was performed covering the available studies on IS, assessing the available data according to their level of evidence, focusing on diagnostic tools, proposed interventions and related outcomes. Results: The data showed high heterogeneity among studies, and lack of evidence on the existence of IS and treatment effectiveness. Conclusion: The syndrome as described, as well as its treatments, require further strong evidence.

RESUMO Background: A síndrome da sensibilidade escotópica, posteriormente denominada síndrome de Meares-Irlen ou simplesmente síndrome de Irlen (SI), foi descrita como indivíduos com sintomas de baixa capacidade de leitura devido à combinação de cores e distorções nas imagens. Indivíduos com essa síndrome podem apresentar leitura lenta e ineficaz, com baixo nível de compreensão e fadiga visual. A fisiopatologia da doença ainda é incerta como uma entidade independente ou como parte do espectro da dislexia. No entanto, tratamentos com lentes e filtros coloridos foram propostos com o objetivo de aliviar o efeito do contraste luminoso e melhorar o desempenho de leitura dos pacientes. Outrossim, nenhuma evidência de eficácia do tratamento foi alcançada. Objetivos: Obter evidências sobre a etiologia, eficácia diagnóstica e intervenção da SI. Métodos: Foi realizada uma revisão sistemática, cobrindo os estudos disponíveis sobre a SI, avaliando os dados disponíveis de acordo com seu nível de evidência, com foco em ferramentas de diagnóstico, intervenções propostas e desfechos relacionados. Resultados: Os dados mostram alta heterogeneidade, falta de evidência sobre a existência da SI e eficácia do tratamento. Conclusões: A síndrome descrita e seus tratamentos exigem evidências mais robustas.

Clinical outcomes of currently available multifocal intraocular lenses

This study investigates the characteristics and clinical outcomes of different types of extended depth-of-focus and multifocal intraocular lenses (IOLs) to determine which IOL can increase patient satisfaction. Modern cataract surgery has undergone tremendous evolution in terms of IOL quality. Recently, different types of presbyopia-correcting IOLs have become commercially available. Among them, multifocal IOLs are the most frequently used. Multifocal IOLs are different from conventional monofocal IOLs because these have multiple focus, which enable patients to see both distant and near objects at the same time. Multifocal IOLs can be classified as either refractive or diffractive IOLs. Diffractive multifocal IOLs include traditional bifocal lenses and relatively new trifocal lenses, and are the most widely used multifocal IOLs owing to their good clinical performance. Trifocal IOLs have an advantage over bifocal IOLs in terms of intermediate visual acuity, but can cause decreased contrast sensitivity and night vision disturbances. Recently developed extended depth-of-focus IOLs are different from traditional multifocal IOLs in that these extend the focus, resulting in smooth continuous focus. It also has the benefit of better contrast sensitivity and improved visual quality over multifocal IOLs; however, is relatively weak in terms of near visual acuity.

The effect of spherical aberration on visual performance and refractive state for stimuli and tasks typical of night viewing / Efecto de la aberración esférica sobre el rendimiento visual y el estado refractivo para los estímulos y tareas típicos de la visión nocturna

Purpose: The aim of this work was to examine the impact of Seidel spherical aberration (SA) on optimum refractive state for detecting and discriminating small bright lights on a dark background. Methods: An adaptive-optics system was used to correct ocular aberrations of cyclopleged eyes and then systematically introduce five levels of Seidel SA for a 7-mm diameter pupil: 0, ± 0.18, and ± 0.36 diopters (D )mm-2. For each level of SA, subjects were required to detect one or resolve two points of light (0.54 arc min diameter) on a dark background. Refractive error was measured by adjusting stimulus vergence to minimize detection and resolution thresholds. Two other novel focusing tasks for single points of light required maximizing the perceived intensity of a bright point's core and minimizing its overall perceived size (i.e. minimize starburst artifacts). Except for the detection task, luminance of the point of light was 1000 cd m-2 on a black background lower than 0.5 cdm-2. Results: Positive SA introduced myopic shifts relative to the best subjective focus for dark letters on a bright background when there was no SA, whereas negative SA introduced hyperopic shifts in optimal focus. The changes in optimal focus were -1.7, -2.4, -2.0, and -9.2 D of focus per D mm-2 of SA for the detection task, resolution task, and maximization of core's intensity and minimization of size, respectively. Conclusion: Ocular SA can be a significant contributor to changes in refractive state when viewing high-contrast point sources typically encountered in nighttime environments

Objetivo: El objetivo de este estudio fue examinar el impacto de la aberración esférica de Seidel (AS) sobre el estado refractivo óptimo para detectar y discriminar las luces brillantes de pequeño tamaño sobre un fondo oscuro. Métodos: Se utilizó un sistema de óptica adaptativa para corregir las aberraciones oculares de ojos bajo cicloplegía, e introducir sistemáticamente cinco valores de AS para una pupila de 7 mm de diámetro: 0, ± 0,18, y ± 0,36 dioptrías (D) mm-2. Para cada valor de AS se solicitó a los sujetos que detectaran un punto de luz, o resolvieran dos puntos (cada punto subtendía 0,54 minutos de arco de diámetro) sobre un fondo oscuro. El error refractivo se midió ajustando la vergencia del estímulo, para minimizar los umbrales de detección y resolución. Los sujetos realizaron además otras dos tareas observando un sólo punto luminoso y en las que tenían que maximizar la intensidad percibida del núcleo del punto luminoso o minimizar el tamaño de la imagen percibida (es decir, minimizar el "starburst"). Excepto para la tarea de detección, la luminancia del punto de luz fue de 1000 cd m-2 sobre un fondo negro con un valor inferior a 0,5 cd m-2. Resultados: La AS positiva introdujo cambios miópicos respecto al mejor enfoque subjetivo para letras oscuras sobre un fondo luminoso sin AS, mientras que la AS negativa introdujo cambios hipermetrópicos respecto al enfoque óptimo. Estos cambios fueron -1,7,-2,4,-2,0, y -9,2 D de enfoque por D mm-2 de AS para la tarea de detección, la tarea de resolución, la maximización de la intensidad del núcleo y la minimización de su tamaño, respectivamente. Conclusión: La AS ocular puede ser un factor que influye significativamente en los cambios en el estado refractivo, al visualizar las fuentes puntuales de alto contraste típicas de los entornos nocturnos

Specific Visual Symptoms and Signs of Meares-Irlen Syndrome in Korean

PURPOSE: To discriminate the visual symptoms and signs of Meares-Irlen syndrome (MIS) and nonspecific dyslexia from other ophthalmologic diseases (NODs). METHODS: Forty-five patients were enrolled. Thirty four of the patients with MIS whose symptoms improved with tinted lenses comprised MIS group. The other 11 patients whose reading difficulty improved with other ocular therapy and did not require tinted lenses comprised NODs group. The main symptoms causing dyslexia and associated ocular diseases were evaluated. RESULTS: The mean age was 17.9 +/- 9.5 years in MIS group, and 19.3 +/- 11.0 years in NODs group. In MIS group, the most common symptoms while reading were difficulty to move lines (85%), doubling (53%), and difficulty in bright condition (27%). On the other hand, blurring was the most common symptom in NODs group (45%). The associated ocular diseases in the two groups were refractive error (79% and 73%), dry eye (29% and 18%), and exophoria (6% and 27%), respectively. CONCLUSIONS: Doubling, difficulty to move lines, and difficulty in bright condition while reading are main specific symptoms in MIS compared to nonspecific dyslexia from other ophthalmologic disorders.

Comparison of Colvardpupillometer, ORBScan II and Sirius in Determining Pupil Size for Refractive Surgery

PURPOSE: To compare pupil size measured by Colvard(R)pupillometer, ORBScan II(R), Sirius(R) and analyze correlation between pupil size and night vision disturbance after refractive surgery according to measuring methods. METHODS: Two hundred eyes of one hundred patients who underwent refractive surgery were retrospectively evaluated. Pupil size was measured with Colvard(R)pupillometer, Sirius(R) in the scotopic light condition and with ORBScan II(R), Sirius(R) in the photopic light condition. Patients filled out questionnaire about night vision disturbance at postoperative three months. Correlation between pupil size according to measuring methods and night vision disturbance was evaluated. RESULTS: The mean age of patient was 26 years and number of male patients was 36. In scotopic light condition, pupil size measured with Colvard(R)pupillometer (6.76 mm) was significantly larger than that of Sirius(R) (6.53 mm) (p < 0.001). In photopic light condition, pupil size measured with ORBScan II(R) (3.98 mm) was significantly smaller than that of Sirius(R) (4.41 mm) (p < 0.001). Night vision disturbance were correlated with pupil size and Sirius(R) in the scotopic light condition had strongest correlation among three measuring method (r = 0.44). CONCLUSIONS: Sirius(R) tends to measure pupil size smaller than Colvard(R)pupillometer in the scotopic light condition. The correlation between night vision disturbance and pupil size was highest in Sirius(R).

Long-Term Quality of Life after Myopic Laser Refractive Surgery

PURPOSE: To investigate long-term satisfaction and quality of life after myopic laser refractive surgery. METHODS: This study included 231 myopic patients who underwent laser refractive surgery (LASIK, LASEK or PRK) at least five years prior, between 2002 and 2005, at 5 hospitals. Using a telephone survey, patients were asked to subjectively answer 26 questions regarding satisfaction, quality of life changes, and visual symptoms. RESULTS: The mean patient satisfaction score was 8.12 (scale of 1 to 10). Improvement in quality of life was reported by 91% of the subjects. Intention to have surgery again was reported by 87.9% of the subjects and intention to recommend refractive surgery to a friend or family was reported by 80.5% of the subjects. The most common discomfort symptoms after myopic laser refractive surgery were dry eye symptoms (57.1%), followed by night vision disturbances (54.3%). CONCLUSIONS: Long-term satisfaction and quality of life were shown to be positive in patients treated with myopic refractive surgery.

Clinical Results and Some Problems of Multifocal Apodized Diffractive Intraocular Lens Implantation

PURPOSE: To evaluate near and far visual outcomes, subjective visual symptoms, and patient satisfaction with AcrySof(R) ReSTOR(R) diffractive multifocal intraocular lenses (IOL), and to study the reasons for postoperative dissatisfaction. METHODS: Twenty-three eyes of 19 patients received phacoemulsifications and implantation of AcrySof(R) ReSTOR(R) IOL. The main outcome measures, taken at postoperative 1 day, 1 week, 1 month, and 3 months, were uncorrected and corrected near and distant visual acuity, refractory errors, subjective visual symptoms (glare, halo, and night vision), and satisfaction. RESULTS: At the 3-month postoperative visit, the mean uncorrected near and distant visual acuities were 0.59+/-0.24 (0.25+/-0.22 LogMAR unit) and 0.78+/-0.27 (0.13+/-0.10 LogMAR unit), respectively. In addition, patients' satisfaction with uncorrected near vision, intermediate vision, far vision, and general visual performance were better than their satisfaction with night vision. Glare and halos were reported as severe by only 10.2% and 5.3% of patients, respectively. The seven eyes with poor patient satisfaction included eyes with a high incidence of preoperative ocular diseases or preoperative and postoperative high corneal astigmatisms of more than 1.0 diopter. CONCLUSIONS: The AcrySof(R) ReSTOR(R) IOL demonstrated good near and distant visual acuity with good patient satisfaction. Previous ocular disease, corneal astigmatism less than 1.0 diopter, and patient lifestyle should be considered to enhance patient satisfaction.

Clinical Outcomes of Wavefront-Guided Epi-LASIK: 6-Months Follow-up

PURPOSE: We evaluate the clinical outcomes after wavefront-guided (WFG) Epi-LASIK in mild and moderate myopia . METHODS: The uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), manifest refraction, total high order aberrations, contrast sensitivity for day and night vision, and pain score in 114 eyes of 61 patients who had undergone WFG Epi-LASIK were measured preoperatively and at 1 day, 1 week, 1 month, 2 months, and 6 months postoperatively. RESULTS: At 1 day, 1 week, 1 month, 2 months and 6 months postoperatively, UCVA & BCVA had improved significantly. At 1 month postoperatively, the spherical equivalent was -0.93+/-0.74 and showed a stable pattern at 6 months postoperatively. There was no statistically significant difference in total high-order aberration between preoperatively measurements and measurements taken at 6 months postoperative (p=0.745). At a frequency of 19 cpd, night contrast sensitivity showed significant statistical difference (p=0.010) but no difference at low and medium frequencies between preoperative measurements and postoperative six months measurements. Pain subsided at 2 weeks postoperative. All patients maintained clear cornea and suffered no complications. CONCLUSIONS: At 6 months postoperatively, patients who underwent Wavefront-guided Epi-LASIK showed successful results for the correction of moderate myopia and excellent contrast sensitivity at night time. Wavefront-guided Epi-LASIK may solve the visual quality problem after refractive surgery and, therefore, may be clinically useful.

Refractive Surgery 2004 in Korea

PURPOSE: This study investigates both the current situation and future trends in the field of refractive surgery in Korea. METHODS: Members of the Korean Society of Cataract and Refractive Surgery (KSCRS) have been annually surveyed regarding cataract and refractive surgery since 1995. The 2004 annual survey, which consisted of 58 multiple-choice questions, was mailed in May 2004 to 322 KSCRS members; fifty-four (16.8%) members responded. Data from the 2004 survey was compared with that of previous annual surveys and similar studies from the USA. RESULTS: The respondents indicated that patients in their forties accounted for the highest percentage (57%) of subjects, and LASIK accounted for the highest percentage (82%) of refractive surgeries. Degeneration of corrected vision, night halo, and glare accounted for a high proportion of the complications arising after refractive surgery. LASIK was the preferred method for treating myopia less than -12 diopters, while phakic IOL was preferred for myopia more than -12 diopters. Lastly, more respondents indicated that they had experienced legal problems associated with PRK or LASIK than the previous year. CONCLUSIONS: LASIK remains the refractive surgery procedure of choice, although wavefront-guided ablation is gaining in popularity. Approximately half of the respondents indicated they used MMC in their refractive surgeries.

Comparison of the Clinical Results of Lensectomy and LASIK for High Myopia

We retrospectively evaluated clinial results of 13 eyes of 8 patients who underwent lensectomy and 11 eyes of 7 patients who underwent LASIK(laser assisted in sity keratomileusis) for correction of high myopia. Clinical outcomes of uncorrected and corrected visual acuity, postoperative refraction, and contrast sensitivity were evaluated. Subjective tests concerning glare, night halos, or decrement of night vision were also performed in each group. Postoperative uncorrected and corrected visual acuities were not significantly different between two groups. Predicatability was significantly higher in lensectomy group than that of LASIK group. Mean contrast sensitivity value of highest frequency(20 cpd) in LASIK group was significantly lower than that in lensectomy group. Subjective glare or night hlaos occurred more in LASIK group. During follow-up, visual loss with 2 lines or more was noted in 2 eyes due to postoperative complications in lensectomy group. No complication occurred in LASIK group. LASIK has been considered reasonably predictable and safe method for correction of high myopia. But our data suggest that lensectomy may give better quality of vision postoperatively compared to LASIK for high myopia. If prophylactic treatments which are aimed to prevention of postoperative complications are carried out prior to lensectomy, lensectomy is a reasonable refractive surgical potion especially for middle-aged patients with high myopia.

The Comparison between 5.0mm and 6.0mm Ablation Diameter in Surgical Result of Excimer Laser Photorefractive Keratectomy

We analyzed the results of 5.0mm and 6.0mm ablation diameter in excimer laser photorefractive keratectomy using the same excimer laser (Aesculap-Meditec, MEL 60, Germany) In 5.0mm ablation diameter group, forty one eyes of thirty five patients were operated from March 1994 to February 1995 and in 6.0mm ablation diameter group, thirty eyes of twenty three patients were operated from July 1995 to December 1995. All were followed for at least 6 months and analyzed by retrospective method. Refractive change, naked visual acuity, corneal haze and night vision difficulties were measured at 1, 3, and 6 months postoperatively. In eyes treated with 6.0mm ablation diameter, the initial hyperopic shift was reduced with significant differences at 1 and 3 months (p.05). The subjective symptoms of night vision difficulty were significantly lower in the 6.0mm treatment group at 1 and 3 months (p=0. 0067, p=0.02). In conclusion, treatment with 6.0mm ablation diameter made less initial hyperopic shift and reduction of side effects in comparison with 5.0mm ablation diameter.

A Comparison of Contrast Sensitivity Between Strabismic and Anisometropic Amblyopia

Contrast sensitivity was measured by MCT 8000(R)(Vistech Consultant INC, U.S.A.) in two groups: 23 strabismic amblyopes and 10 anisometropic amblyopes. In general, the amblyopic eyes exhibited a statistically significant loss of contrast sensitivty in both day and night vision. When visual acuity was equated between groups, the anisometropic group had a greater loss of contrast sensitivity at the high spatiaI frequencies and the strabismic group exchibited a similar loss of contrast at all spatial frequencies. Test-retest correlations(average 0.76) were statistically significant, which demonstrated that the test using MCT 8000(R) was reliable.

The Aasesament of Contrast Sensitivity by MCT 8000(R) in Normal Eyes and Peeudophakic Eyes

The standard vision test using Snellen acuity is not always an accurate indicat or of functional vision loss. Acuity measures optical blur, but psudophakic eyes frequently do not affect optical blur. Therefore, acuity cannot provide relevant informations on the loss of vision experienced by the patients. Contrast sensitivity, not acuity, has been shown to be effective in determining functional vision loss due to psudophakic eyes. The MCT 8000(R), glare and contrast sensitivity system. was used for measurement of contrast sensitivity in 19 pseudophakic eyes at postoperative 1 month, 18 pseudophakic eyes at post-operative 3 months and 18 normal control eyes. The results were as follows: 1) Contrast sensitivity decreased in pseudophakic eyes compared to normal eyes in four different conditions; day vision, day vision with perpheral glare, night vision and night vision with central glare. 2) In pseudophakic eyes, contrast sensitivity was not different between 1 month and 3 months postoperatively.