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PubMed2002

Incisional refractive surgery.

The use of incisional refractive surgery has become limited due to the widespread use of the excimer laser to correct myopia, hyperopia and astigmatism. Laser in situ keratomileusis and photorefractive keratectomy have proven to be much more accurate and predictable in correcting refractive error. This has made some forms of incisional refractive surgery practically obsolete. Radial keratotomy should not be considered a primary refractive procedure in the modern world, as RK has become "RKhaic". There are still indications for incisional refractive surgery in cataract and post-surgical patients for the treatment of astigmatism. However, with the advent of the toric intraocular lens and the use of LASIK in such aforementioned patients, these indications for incisional surgery will likely become more limited. In this review, we go over the past history of incisional refractive surgery and also report the current uses and advancements of this technique in today's practice environment.

Astigmatism↗
PubMed2005

Lenticular accommodation in relation to ametropia: the chick model.

Our goal was to determine whether experimentally induced ametropias have an effect on lenticular accommodation and spherical aberration. Form-deprivation myopia and hyperopia were induced in one eye of hatchling chicks by application of a translucent goggle and +15 D lens, respectively. After 7 days, eyes were enucleated and lenses were optically scanned prior to accommodation, during accommodation, and after accommodation. Accommodation was induced by electrical stimulation of the ciliary nerve. Lenticular focal lengths for form-deprived eyes were significantly shorter than for their controls and accommodation-associated changes in focal length were significantly smaller in myopic eyes compared to their controls. For eyes imposed with +15 D blur, focal lengths were longer than those for their controls and accommodative changes were greater. Spherical aberration of the lens increased with accommodation in both form-deprived and lens-treated birds, but induction of ametropia had no effect on lenticular spherical aberration in general. Nonmonotonicity from lenticular spherical aberration increased during accommodation but effects of refractive error were equivocal. The crystalline lens contributes to refractive error changes of the eye both in the case of myopia and hyperopia. These changes are likely attributable to global changes in the size and shape of the eye.

Accommodation, Ocular↗
PubMedDate not supplied

Myopia predicts better outcome in persistent hyperplastic primary vitreous.

PURPOSE: Persistent hyperplastic primary vitreous (PHPV) is a congenital disorder that presents with a spectrum of ocular anomalies, including cataracts, microphthalmia, and hyaloid vessel remnants. Severe visual loss due to secondary glaucoma and retinal detachment is common. This report evaluates the visual outcome of a variant of PHPV with myopia not associated with glaucoma. METHODS: The records of 23 consecutive patients with the diagnosis of PHPV (all unilateral) from October 1992 to August 1995 were reviewed. All but three patients had a cataract extraction procedure and all underwent amblyopia therapy. Eyes with a phakic myopic refractive error (Rx) or aphakic refractive correction < or = 8.5 diopters (D) in the immediate postoperative period were designated as myopic. RESULTS: Six patients were in the myopic group (Group 1) and 17 in were the nonmyopic group (Group 2). The mean age of diagnosis was 21.1 months in Group 1 versus 2.0 months in Group 2, with a comparable follow-up period of 36 months. The mean preoperative Rx of Group 1 was -7.78 D. The mean aphakic Rx of Group 2 was +18.29 D. Average axial length measurement determined by echography was 22.46 mm in Group 1 and 14.03 mm in Group 2. The mean corneal diameter was 11.3 mm in Group 1 vs 8.9 mm in Group 2. In Group 2, seven eyes developed retinal detachment and four developed glaucoma. These complications did not develop in Group 1 during the follow-up period. Overall functional visual acuity was better in Group 1, with a median visual acuity at final follow up of 20/160, as compared with light perception for Group 2. CONCLUSIONS: PHPV eyes with myopia were not detected as early as the typical PHPV eyes, primarily because of less media opacification and near-normal corneal diameters. These eyes showed a more favorable visual outcome as they were less likely to develop typical PHPV-related postoperative complications. Myopic PHPV eyes may require a different management approach.

Child, Preschool↗
PubMed1978

[The random dot test as a screening method for the visual acuity in children (author's transl)].

The Random Dot Test was used for a screening of the visual acuity of children of 6 to 10 years of age. The testing time is reduced by 50% as compared with the examination by means of illiterate E images on cardboard charts. Children with refractive errors of up to 3 delta but normal visual acuity after correction are not detected at the examination distance of 1.30 m used in this study. None out of 672 children with severe eye diseases gave false negative results with the Random Dot Test. Disturbances of the binocular vision could also be detected with the Random Dot Test.

Child↗
PubMed1977

Comparison of "near retinoscopy" and subjective refraction in adults.

Static retinoscopy can yield contaminated results because the central rays of the retinoscope beam are oblique with respect to the line of sight of the eye being examined. Additionally, it is difficult to obtain steady distant fixation by children and infants. A near-retinoscopy technique is described, and refractive errors obtained by subjective refraction and near retinoscopy on adults are compared to show that the latter technique yields reliable and valid measures of refraction.

Adult↗
PubMed1984

[Fundus asymmetry--supertraction of the papilla and posterior sclera staphyloma--as a source of error in the calculation of intraocular lenses].

The evaluation of 404 consecutively implanted posterior-chamber intraocular lenses after extra-capsular cataract extraction revealed a mean post-operative refractive error of + 0.52 diopters with a standard deviation of +/- 1.27 diopters. Four calculations attracted attention because of their unusually high refractive error of + 3.4 diopters. A post-operative refractive balance excluded measurement or calculation errors. On the other hand, repeated axial length measurements on these four eyes showed a very high mean variation of 3.27 mm. This high variation can be correlated to such typical elevation changes of the central fundus as a tilted disc or posterior staphyloma. High axial length measurements which do not correspond to appropriate amounts of axial myopia should be handled carefully to avoid high amounts of hyperopia following intraocular implantation.

Fundus Oculi↗
PubMedDate not supplied

Comparison of on- and off-axis photorefraction with cycloplegic retinoscopy in infants.

We have compared the performance of an off-axis (knife-edge) photorefractor with that of an on-axis (isotropic) system. Normal infants and children between the ages of 8 and 208 weeks were photographed with each camera both with and without cycloplegia. Refractive errors were estimated for each technique based on equations derived from ray-tracing. These refractions were compared to the results of retinoscopy under cycloplegia. Sensitivity and specificity of the two photorefraction systems were evaluated as a function of the magnitude of meridional hyperopia defined by retinoscopy. We also examined the effect of varying the photorefraction screening criterion. Thirteen percent of the infants in the screening sample presented with +3.50 diopters or more of meridional hyperopia. Using this level of ametropia as a referral criterion, the sensitivity and specificity of the off-axis system for infants without cycloplegia were 83% and 72%, respectively. For the on-axis system, sensitivity and specificity values were 85% and 53%. The use of cycloplegics did not significantly improve the performance of either system, but rather their use degraded the specificity of the on-axis system in the presence of moderate refractive errors. The results of the present study indicate that both on- and off-axis systems are effective in identifying highly ametropic infants, but that the off-axis system results in significantly fewer false positives. Moreover, the off-axis system has the advantages of an inherently greater dynamic range for a fixed camera design, and also more easily interpreted photographs.

Child, Preschool↗
PubMed2003

Neural pathways subserving negative lens-induced emmetropization in chicks--insights from selective lesions of the optic nerve and ciliary nerve.

PURPOSE: Active emmetropization describes the process by which young eyes regulate their growth to eliminate refractive errors. The purpose of this study was to re-investigate the role of the brain in compensation to imposed hyperopic defocus (negative lenses), specifically, to assess whether a retina-brain link and/or an intact ciliary nerve are required for this emmetropizing response. Data from previous related studies are equivocal. METHODS: Unilateral lesion surgery involving either or both optic nerve section (ONS) and ciliary nerve section (CNS), was performed on 2-3 day old White-Leghorn chicks to interrupt communication between the eye (retina in the case of ONS) and brain. After a recovery period of 4 days, lesioned eyes were fitted with either -5 or -15 D lenses or diffusers (6-9 per group). An additional lesion group underwent unilateral CNS and was fitted with -5 D lenses bilaterally. Finally 3 groups that underwent the same unilateral optical treatments but no surgery were included as controls for analyzing lesion-induced changes. Complete sets of measurements, involving retinoscopy for refractive errors, and high frequency A-scan ultrasonography for axial ocular dimensions, were made at the beginning (baseline), and end of a 4 day treatment period. Additional ultrasonography data were collected after 1 and 2 days of treatment. Optical treatment effects were expressed as changes in interocular differences from baseline values. RESULTS: All three lesions produced hyperopic shifts in refraction (evident in baseline values), although this effect was minimal for the ONS+CNS group. Choroidal thickening as well as increased anterior chamber depth and lens thinning were observed in all cases but vitreous chamber depth was reduced in only the ONS group. In response to the -5 D lens, the control (nonlesioned) group showed nearly complete compensation, while full compensation was not achieved to the -15 D lens over this short treatment period. The diffuser group showed the largest change, which was also in the direction of myopia. Both the ONS and CNS groups showed near normal compensation, as indexed by the changes in refractive errors relative to their respective baseline values. In contrast, the ONS+CNS lens groups overcompensated, by 130% and 54% for the -5 D and the -15 D lens groups respectively. Form deprivation responses were slightly exaggerated in both ONS and ONS+CNS groups, the latter group again showing the largest response. Enhanced vitreous chamber growth was evident under all conditions and correlated well with the refractive changes across the groups. DISCUSSION: The data imply that an intact retina-brain link is not required for compensation to hyperopic defocus and thus emmetropization. However, the data also imply interactions between higher centers and the eye. The emmetropization set-point appears to be recalibrated after ONS surgery. The data also indicate a role of the ciliary nerve as an important conduit for signals that exercise a restraining influence on eye growth.

Accommodation, Ocular↗
PubMed2003

A clinical evaluation of ophthalmic assessment in children with sensori-neural deafness.

BACKGROUND: Since 1991, children with sensori-neural deafness and their families within Southern Derbyshire have been supported by a multiagency approach to their diagnosis and management. RESULTS: One hundred and twenty-two children were seen at the Child Development Centre for an holistic assessment, and 110 of these children have had an ophthalmic assessment, of whom 48 (43.6%) were found to have ophthalmic abnormalities. These included 43 children (39.1%) with refractive errors, ranging from mild to severe. Of 82 children with uncomplicated deafness, 26 (31.7%) had refractive errors. The prevalence of ophthalmic problems was higher than the prevalence in hearing school children in the literature and in local pre-school children. There were six cases of Usher syndrome. Twenty-one children had more than one eye defect. The findings indicate that deaf and hearing impaired children are two to three times more likely to develop ophthalmic abnormalities than their hearing peers, which makes early detection of paramount importance. An important local outcome has been the establishment of guidelines for ophthalmic assessment to include assessment of vision and screening for Usher syndrome by electro-physiological testing at aged 7 years and above. Screening has been completed to date in 78 children with congenital sensori-neural deafness. CONCLUSIONS: Sensitive and efficient ophthalmic assessment and management are essential for all deaf and hearing impaired children and national guidelines need to be established for both assessment of vision and screening for Usher syndrome, based on further evaluated research.

Child↗
PubMed2006

Potential complications of ocular surgery in patients with coexistent keratoconus and Fuchs' endothelial dystrophy.

PURPOSE: To describe the potential complications of cataract and refractive surgery in patients with Fuchs' endothelial dystrophy (FED) and keratoconus. DESIGN: Retrospective case series. PARTICIPANTS: Eight patients with FED and keratoconus in a large university group practice. METHODS: We reviewed the clinical and topographic findings of 8 patients (15 eyes) with FED and keratoconus. Clinical examination, corneal topography, specular microscopy were done, and sequential central corneal thickness (CCT) was obtained. Follow-up ranged from 1 month to 6 years. MAIN OUTCOME MEASURES: Findings of keratoconus and FED in preoperative evaluation. RESULTS: Five patients had concomitant cataracts; 3 had refractive errors and sought surgical correction. Cataract surgery was performed on 3 of 5 patients (5 eyes). LASIK was performed on one eye of 3 patients. Of 5 eyes that underwent cataract extraction, 4 had blurry vision after surgery. The interval between the surgical procedure and onset of symptoms ranged from 1 month to 4 years. The causes of decreased vision after cataract surgery were corneal edema and/or corneal ectasia. The CCT readings ranged from 426 to 824 microm. One of 4 symptomatic eyes underwent penetrating keratoplasty. The CCTs of 3 patients (6 eyes) who presented with refractive error ranged from 507 to 565 microm. One eye had undergone an attempted LASIK procedure resulting in a lost cap. Corneal topography and specular microscopy showed the coexistence of keratoconus and FED, and the patients were advised against having LASIK surgery. CONCLUSIONS: Corneal thinning caused by keratoconus and concurrent increase in corneal thickness caused by FED may combine to normalize the corneal pachymetry readings; disease severity may be underestimated, which may lead to unexpected postoperative visual outcomes. Routine use of preoperative topography and specular microscopy may help to avert potential surgical complications.

Aged↗
PubMed2001

Pigmented striae of the anterior lens capsule and age-associated pigment dispersion of variable degree in a group of older African-Americans: an age, race, and gender matched study.

PURPOSE: To investigate pigmented striae of the anterior lens capsule in African-Americans, a potential indicator of significant anterior segment pigment dispersion. METHODS: A group of 40 African-American subjects who exhibited pigmented lens striae (PLS) were identified from a non-referred, primary eye care population in Chicago, IL, USA. These subjects were then compared to an age, race, and gender matched control group relative to refractive error and the presence or absence of diabetes and hypertension. RESULTS: The PLS subjects (mean age = 65.4 +/- 8.8 years, range = 50-87 years) consisted of 36 females and 4 males. PLS were bilateral in 36 (85%) of the 40 subjects. Among the eyes with PLS, 21 (55%) of 38 right eyes and 22 (61%) of 36 left eyes also had significant corneal endothelial pigment dusting, commonly in the shape of a Krukenberg's spindle. Ten (25%) of the PLS subjects had either glaucoma or ocular hypertension (7 bilateral, 3 unilateral). The presence of trabecular meshwork pigment varied from minimal to heavy. The mean +/- SD (range) refractive error of the PLS right eyes was +1.61 +/- 1.43D (-1.50 to +5.00D) and +1.77 +/- 1.37D (-1.00 to +5.00D) for the left eyes. Based on these data, the PLS right eyes were +1.63D (Student's t, p = 0.0001; 95% CI = +0.82 to +2.44D) more hyperopic on average than the control right eyes, and the PLS left eyes were +1.77D (p = 0.0001; 95% CI = +0.92 to +2.63D) more hyperopic on average than the control left eyes. Trend analysis showed a gradually increasing likelihood of PLS with increasing magnitude of hyperopia in both eyes (Mantel-Haenszel chi-square, p = 0.001). Among PLS subjects, 24 (60%) of 40 were hypertensive and 9 (23%) of 40 were diabetic. However, these proportions were not significantly different (two-tailed Fisher's exact test; hypertension: p = 0.30; diabetes: p = 0.70) from the randomly selected controls. CONCLUSIONS: Among our African-American group, which consisted predominately of females >50 years of age, the likelihood of PLS increased with increasing hyperopic refractive error. This finding is consistent with the possibility that PLS may, in some circumstances, indicate a significant pigment dispersal process due to iris-lens rubbing that may be associated with crowding of anterior segment structures. Additional study is warranted to further assess the nature of PLS, their precise relationship with an age-related pigment dispersal process, and their true significance as a risk factor for development of glaucoma.

Adolescent↗
PubMed2004

Efficacy of spectacles in persons with albinism.

INTRODUCTION: Patients with albinism have varying degrees of reduced vision, strabismus, iris transillumination, nystagmus, fundus hypopigmentation, and foveal hypoplasia. High refractive errors are common, but reduced vision persists due to nonrefractive factors, causing reluctance by some clinicians to prescribe spectacles. We sought to evaluate the effect of spectacle correction of refractive error on clinical findings and recorded compliance with refractive corrections, as little detailed data exist. METHODS: We prospectively examined 35 consecutive patients with albinism for whom glasses had been prescribed to determine if objective improvement in recognition visual acuity (VA), strabismus, anomalous head posture (AHP), fusion, or stereoacuity occurred with refractive correction. Parents or patients reported compliance with glasses wear (excellent: >75% of awake hours; good: 50-75% of awake hours; fair: 26-50% of awake hours; poor: <25%). RESULTS: Median age was 9.5 years (range: 3 to 30). Median refractive correction was 1.875 D spherical equivalent (range: -9.75 to +8.88 D). Glasses wear was initiated at a median age of 14 months (range: 3 months to 14 years). Mean binocular VA at distance was 20/80.9 corrected and 20/107.6 uncorrected ( P < 0.001). Mean VA at near was 20/28.4 corrected and 20/41 uncorrected ( P < 0.001). Mean strabismic deviation was 7.2 PD with glasses and 10.0 PD without glasses at distance ( P = 0.006) and 10.8 PD with glasses and 14 PD without glasses at near ( P = 0.042). Mean AHP at distance was 8.3 degrees with glasses and 7.3 degrees without glasses at distance ( P = 0.327) and 4.7 degrees both with and without glasses at near ( P = 0.308). Twenty-one patients had fusion with or without glasses, two had fusion only with glasses, and one patient had fusion only without glasses. The other patients did not have any detectable degree of fusion. Twenty-seven individuals had no stereoacuity with or without glasses, five had gross stereoacuity of 3000 seconds of arc both with and without glasses, and three had gross stereoacuity only while wearing glasses. Compliance was excellent in 29 patients, fair in four, and poor in two. CONCLUSION: This prospective study showed a significant improvement in corrected VA and alignment in persons with albinism, despite overall subnormal acuity. Some individuals also experienced improvement in binocular alignment and AHP. Compliance with spectacles was generally good. Therefore, refractive correction should be encouraged in persons with albinism as improvement in visual function is likely to occur.

Adolescent↗
PubMed2001

Comparison of refractive state and circumferential morphology of retina, choroid, and sclera in chick models of experimentally induced ametropia.

PURPOSE: Simultaneous comparisons of the circumferential morphological tissue profiles and final refractions from form-deprivation myopia (FDM), defocus-induced myopia (DIM), and defocus-induced hyperopia (DIH) models of ametropia have been made to test the hypothesis that changes in the thickness profiles of the three coats of the eye, and particularly that of the choroid, can be predicted from the degree of induced refractive error. METHODS: Hatchling chickens (n = 23) were raised for 2 weeks wearing either a monocular translucent diffuser (FDM, n = 8), monocular -10.00 D lens goggle (DIM, n = 7), monocular +10.00 D lens goggle (DIH, n = 7), or nothing (Norm, n = 1). All animals were refracted using retinoscopy and were then sacrificed, and whole eyes were processed for scanning electron microscopy. Retinal, choroidal, and cartilaginous sclera (CS) thickness measurements were made from photographic collages of the entire circumference of the globe. Of the 23 chickens, complete morphological profile data were available for both eyes of 10 animals (nine treated and one normal). The contralateral fellow eyes (FEyes) of all nine experimental chickens were used as experimental controls as paired comparisons for statistical analyses. RESULTS: Morphological profiles of control and experimental eyes revealed significant systematic regional variations in tissue thickness. This variation was related to nasal or temporal eccentricity with the nasal side generally thinner than the temporal. Retinal, choroidal, and CS tissue from FDM and DIM eyes showed very similar anatomical responses despite significantly different degrees of refractive change. DIH eyes showed significant increases in choroidal thickness but none in retinal or CS thickness. Analysis of fellow control eyes indicated that in both myopia models (FDM and DIM), significant changes in all tissues of the untreated fellow eyes occur whereas only the choroid of the fellow eye was affected in the hyperopic (DIH) model. CONCLUSIONS: The morphological similarity observed in the circumferential profiles of the retina, choroid, and cartilaginous sclera of the FDM and DIM eyes despite approximately 20 D difference in final refraction suggests that choroidal thickness is not a good predictor of final refractive error across models. Similarly, the final refractive difference of approximately 20 D between the DIM and the DIH eyes did not receive a major contribution from the final difference in choroidal thickness (with its implied effect on vitreous chamber length).

Animals↗
PubMed1998

Spectacle lenses and emmetropization: the role of optical defocus in regulating ocular development.

The purpose of our investigation was to determine whether early ocular growth and refractive development was regulated by visual feedback in infant monkeys. Specifically, we examined the ability of infant monkeys to compensate for optically induced changes in the eye's refractive state and to recover from experimentally induced refractive errors. For moderate-powered anisometropic lenses, infants exhibited differential interocular axial growth rates that reduced the lens-induced refractive imbalance between the two eyes. Infants treated with equal-powered lenses over both eyes also showed compensating growth. For lens powers between approximately -3 and +6 D, the resulting refractive-error changes, which were primarily due to alterations in vitreous chamber growth rates, were well correlated with the effective refractive state produced by the treatment lenses. When the stimulus for altered eye growth was removed and the infants were provided unrestricted vision, monkey eyes consistently grew toward emmetropia. The remarkable degree of adaptability exhibited by the eyes of infant monkeys demonstrates that emmetropization in this higher primate is an active process that is regulated on a continuous basis by optical defocus. Consequently, early in life spectacle lenses by changing the eye's effective focus can predictably alter ocular growth and the refractive status of one or both eyes.

Animals↗
PubMed2003

The Tehran Eye Study: research design and eye examination protocol.

BACKGROUND: Visual impairment has a profound impact on society. The majority of visually impaired people live in developing countries, and since most disorders leading to visual impairment are preventable or curable, their control is a priority in these countries. Considering the complicated epidemiology of visual impairment and the wide variety of factors involved, region specific intervention strategies are required for every community. Therefore, providing appropriate data is one of the first steps in these communities, as it is in Iran. The objectives of this study are to describe the prevalence and causes of visual impairment in the population of Tehran city; the prevalence of refractive errors, lens opacity, ocular hypertension, and color blindness in this population, and also the familial aggregation of refractive errors, lens opacity, ocular hypertension, and color blindness within the study sample. METHODS DESIGN: Through a population-based, cross-sectional study, a total of 5300 Tehran citizens will be selected from 160 clusters using a stratified cluster random sampling strategy. The eligible people will be enumerated through a door-to-door household survey in the selected clusters and will be invited. All participants will be transferred to a clinic for measurements of uncorrected, best corrected and presenting visual acuity; manifest, subjective and cycloplegic refraction; color vision test; Goldmann applanation tonometry; examination of the external eye, anterior segment, media, and fundus; and an interview about demographic characteristics and history of eye diseases, eye trauma, diabetes mellitus, high blood pressure, and ophthalmologic cares. The study design and eye examination protocol are described. CONCLUSION: We expect that findings from the TES will show the status of visual problems and their causes in the community. This study can highlight the people who should be targeted by visual impairment prevention programs.

Blindness↗
PubMedDate not supplied

Ophthalmic screening of school children in Ankara.

Ophthalmic screening was done on 23,810 children visited at schools in different regions of Ankara. Children with below normal visual acuity were invited to the outpatient department and had a full routine ocular examination. Thirty-nine nursery and primary schools were selected, ten of them private, eleven average state schools, seven good state schools and eleven village schools. Among the 23,810 children, 3095 (13%) had various pathology; 1516 were girls, 1579 boys. Refractive errors were found in 85% of the children (2630). This equals 11% of the total screened population. Refractive errors were myopia 32%, hypermetropia 21%, astigmatism 47%. Strabismic children were 2.5%, and amblyopia was found in 1.1%. The purpose of the study was to assess the place of an ocular screening program in primary school children and to discuss the differences encountered in different urban areas.

Age Distribution↗
PubMed1996

Long-term follow-up of ocular findings in children with Stickler's syndrome.

PURPOSE: To document the longitudinal changes in eye status of children diagnosed with Stickler's syndrome in the first decade of life. METHOD: All patients with cleft palate were referred for eye examination. Of these, patients with systemic findings of Stickler's syndrome were included in this report. RESULTS: Thirty-four eyes in 17 patients met inclusion criteria, with median best-corrected recognition acuity of 20/30. The mean cycloplegic refraction at presentation was -5.00 diopters, and the mean refraction at last visit was -5.50 diopters. CONCLUSIONS: Refractive errors, cataracts, and vitreoretinal abnormalities can be detected early in life in patients with Stickler's syndrome, and refractive error changed little during the follow-up period.

Cataract↗
PubMed1992

Glenn A. Fry Award Lecture 1991: perceptual manifestations of imperfect optics in the human eye: attempts to correct for ocular chromatic aberration.

The profession of optometry has been very successful in providing optical corrections for spherocylindrical refractive errors. In this paper, I examine one attempt to improve retinal image quality beyond that afforded by a standard refractive correction. Ocular chromatic aberration is one of the factors that prevent retinal image quality from reaching the upper limit set by the wave nature of light. It can be subdivided into three primary aberrations (wavelength-dependent differences in imaging plane, image position, and image size). We have been able to measure all three of these using psychophysical techniques. Although attempts to provide an optical correction for wavelength-dependent refractive errors have been optically successful, they have failed to improve vision. Several possible explanations are given for this failure.

Awards and Prizes↗