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PubMedDate not supplied

An ophthalmoscope is not a retinoscope. The difference is in the red reflex.

Both the retinoscope and the ophthalmoscope allow observation of the fundus and of the "red reflex." Retinoscopy, however, requires an effective light source that may be quickly moved off the visual axis. The ophthalmoscope is unable to provide this type of illumination. On the other hand, the retinoscope is unable to provide sufficient illumination of the retina to make it useful for ophthalmoscopy . Ophthalmoscopy requires the examiner's retina to be conjugate to the retina being examined, whereas the examiner's retina becomes conjugate to the peephole of the retinoscope in retinoscopy. The "red reflex" seen with either the retinoscope or the ophthalmoscope may be clear or blurred. The clear red reflex is more useful for ophthalmoscopy , while the blurred red reflex is primarily used for retinoscopy.

Humans↗
PubMed1992

Refractive state, corneal curvature, accommodative range and ocular anatomy of the Asian elephant (Elephas maximus).

The resting refractive state of six mature, female, Asian elephants (Elephas maximus) was determined using streak retinoscopy and neutralizing video retinoscopy. The amplitude of accommodation was also measured by neutralizing video retinoscopy of two animals and the corneal curvatures of three animals was measured by photokeratoscopy. The net spherical refraction was found to be +0.23 D. No difference was observed between cyclopleged and non-cyclopleged eyes (data from three animals), nor was there any difference between right and left eyes. Nine of the twelve eyes refracted had > or = 0.5 D astigmatism. The mean corneal power, as measured by photokeratometry was 21.3 D (SD = 1.8 D). There was a tendency towards with-the-rule corneal astigmatism in our sample (mean value: 1.2 D), though it did not reach statistical significance (P = 0.06). Two elephants were examined using neutralizing video photoretinoscopy. They were able to accommodate through 3 D. Three fixed eyes from three different elephants were obtained for gross and microscopic examination. The mean axial length of the eye was 38.75 mm and the lens had an axial diameter of approx. 10 mm. The posterior sclera was thick (8.0-8.5 mm). Histologically, the cornea was comprised of five distinct layers. A thin, meridionally oriented smooth ciliary muscle was identified. Individual muscle fibers were also observed associated with the posterior trabeculae of the uveal meshwork.

Accommodation, Ocular↗
PubMed1986

Automated refraction in aphakia--II. Its repeatability and accuracy compared to conventional techniques.

The repeatability and accuracy of an i.r. electronic optometer (the Ophthalmetron) and of retinoscopy performed by experienced practitioners were studied in aphakia by testing a group of 17 patients three times with each method and by subjective techniques. The results show that the Ophthalmetron gives better repeatability than retinoscopy and that accuracy is marginally better for the sphere with the Ophthalmetron and for the cylinder power by retinoscopy when the mean of the three subjective results is taken as the true refractive value.

Adult↗
PubMed2001

Use of the HARK autorefractor in children.

PURPOSE: We investigated the reliability, accuracy, and repeatability of an autorefractor with the capability of over-refracting and measuring visual acuity for use in children in a prospective study. METHODS: Before and after cycloplegia, 68 children (mean +/- SD age, 10 +/- 3 years, range 5-16 years) underwent autorefraction twice with the HARK 599 Autorefractor (Humphrey Instruments Inc., San Leandro, CA), subjective over-refraction through the HARK autorefractor, and subjective refraction using a phoro-optometer. After cycloplegia, retinoscopy was performed. Results are reported for one eye (left) of each child. RESULTS: For 68 eyes of 68 children, before and after cycloplegia, correlation coefficients (R) for autorefraction reproducibility exceeded 0.95 for all comparisons of sphere and cylinder. R for spherical values for autorefraction vs. over-refraction was 0.93 and vs. subjective refraction 0.83 before cycloplegia and 0.94 and 0.97 after cycloplegia. Comparing values before and after cycloplegia, autorefraction, over-refraction, and subjective refraction, the data correlated > 0.81 for sphere and 0.75 to 0.87 for cylinder. Cycloplegic retinoscopy compared with autorefraction, over-refraction, and subjective refraction had R > 0.86 for sphere and cylinder for all comparisons except one. Cycloplegia increased the proportion of spherical equivalent values within 0.625 D of the subjective refraction from 41 of 68 eyes (61%) for auto- and over-refraction to 64 (94%) and 51 (75%) of the 68 eyes, respectively. A visual acuity of 20/30 or better was produced in 50 of 68 (73%) eyes with automated refraction before and after cycloplegia and in 62 (92%) with subjective refraction before cycloplegia and subjective refraction and retinoscopy after cycloplegia. Subjective over-refraction did not significantly improve the visual acuity. CONCLUSIONS: In children, HARK autorefraction improved in accuracy, when compared to subjective refraction, and the level of visual acuity improved after cycloplegia. Over-refraction through the instrument did not improve the results before or after cycloplegia.

Adolescent↗
PubMedDate not supplied

Does a tilted retina cause astigmatism? The ocular imagery and the retinoscopic reflex resulting from a tilted retina.

An astigmatic dial viewed by a tilted retina will have only one line in focus, simulating astigmatic blur. We compare and contrast this optical situation to actual astigmatism. Photographs were taken of an astigmatic dial blurred with a cylindrical lens, and also of the same astigmatic dial tilted, simulating tilted retinal imagery. A model eye for retinoscopy practice was provided with a retina tilted 30 degrees and was retinoscoped repeatedly with and without added confounding cylinder by five skilled retinoscopists. Photographs of the astigmatically blurred and tilted astigmatic dials were similar but not identical, as expected. The model eye with tilted retina showed no astigmatism by retinoscopy in 14/15 measurements and 0.25 D of astigmatism in one measurement. When confounding cylinder was present, the retinoscopic measurement was always within 0.25 D of the added cylinder. The ocular imagery resulting from a tilted retina can simulate astigmatic blur, but this is actually due to a type of curvature of field. Only a minute area of the tilted retina is viewed during retinoscopy, so the tilt has essentially no influence on the retinoscopic reflex.

Adult↗
PubMed1994

Screening of infants for significant refractive error using videorefraction.

Isotropic photorefraction has been suggested as a suitable method for screening infants for refractive error. Recently published data suggested that reasonable consistency with retinoscopy results might be achieved using cycloplegic videophotorefraction (VPR) for spherical refractive error but that results might be unreliable for astigmatic errors. Non-cycloplegic VPR did not appear to produce results consistent with retinoscopy. A practical idea of how many children might be identified using this technique and how many missed was needed by personnel designing screening projects. Hence the VPR was tested by screening a population of 247 infants for significant refractive error, and comparing the results with cycloplegic retinoscopy. Sensitivity and specificity scores were calculated for a range of test levels of ametropia. Without cycloplegia, sensitivity of VPR was poor. With cycloplegia the situation was much improved, with sensitivity for hyperopia +4.00 D or over of 83.3% and specificity of 90.6%. Sensitivity for astigmatism of 1 D or greater (84.6%) was high but specificity was poor (45.6%). Acceptable sensitivity was achieved for identifying children in this age group at risk of developing squint and amblyopia due to refractive error, providing cycloplegia was used.

Amblyopia↗
PubMed1998

Ophthalmological long-term follow up of preterm infants: a population based, prospective study of the refraction and its development.

BACKGROUND: Numerous studies have reported an increased risk of refractive errors in prematurely born infants, but only few have been long-term and strictly population based. METHODS: A 3.5 year ophthalmological long term follow up of 248 preterm infants was performed. The infants had been included in a previous epidemiological study of retinopathy of prematurity (ROP) (birth weight < or = 1500 grams). The incidence of refractive errors and development of refraction were studied, based on retinoscopies at 6 and 30 months of corrected age. RESULTS: The overall incidence of myopia was 8% at 6 months, of which 35% was transient, and 10% at 30 months. Of the cryotreated infants, 30-40% were myopic at both retinoscopies. The incidence of astigmatism was 52% at 6 months and 26% at 30 months. Astigmatism was associated with ROP, but not with cryotreated ROP itself. Astigmatism "against the rule" was commoner than astigmatism "with the rule". Anisometropia occurred in 6.5% of the infants at 6 months and in 8.4% at 30 months. The incidence of anisometropia was higher in eyes with ROP, particularly in cryotreated eyes, which tended to have high and persistent anisometropia. CONCLUSION: The risk of refractive errors is higher in preterm infants than in infants born at term, and also prematurely born infants without ROP do run an increased risk of having myopia and anisometropia. We recommend follow up examinations with retinoscopy for all infants included in screening programmes for ROP.

Anisometropia↗
PubMed1999

Screening for refractive errors in children: accuracy of the hand held refractor Retinomax to screen for astigmatism.

AIMS: To assess the reliability of the hand held automated refractor Retinomax in measuring astigmatism in non-cycloplegic conditions. To assess the accuracy of Retinomax in diagnosing abnormal astigmatism in non-cycloplegic refractive screening of children between 9 and 36 months. METHODS: Among 1205 children undergoing a non-cycloplegic refractive screening with Retinomax, 299 (25%) had repeated non-cycloplegic measurements, 302 (25%) were refracted under cycloplegia using the same refractor, and 88 (7%) using retinoscopy or an automated on table refractor. The reproducibility of non-cycloplegic cylinder measurement was assessed by comparing the cylindrical power and axis values in the 299 repeated measurements without cycloplegia. The influence of the quick mode on cylinder measurement was analysed by comparing the cylinder and axis value in 93 repeated measurements without cycloplegia where normal mode was used in one measurement and quick mode in the other. Predictive values of the refractive screening were calculated for three different thresholds of manifest astigmatism (> or = 1.5, > or = 1.75, and > or = 2 D) considering as a true positive case an astigmatism > or = 2 D under cycloplegic condition (measured by retinoscopy, on table, or hand held refractor). RESULTS: The 95% limits of agreement between two repeated manifest cylinder measurements with Retinomax attained levels slightly less than plus or minus 1 D. The 95% limits of agreement for the axis were plus or minus 46 degrees. The comparison of non-cycloplegic measurements in the quick and normal mode showed no significant difference and 95% limits of agreement plus or minus 0.75 D. The mean difference between non-cycloplegic and cycloplegic cylinder values measured by Retinomax reached 0.17 D and was statistically significant. Manifest thresholds of > or = 1.5 D, > or = 1.75 D, > or = 2 D cylinder value diagnosed 2 D of astigmatism under cyclplegia respectively with 71-84%, 59-80%, 51-54% of sensitivity (right eye-left eye) and 90-92%, 95%, 98% of specificity. CONCLUSION: Without cycloplegia, Retinomax is able to measure cylinder power with the same reproducibility as cycloplegic retinoscopy. No significant difference was found in the cylinder values obtained with the quick and the normal modes. Therefore, the quick mode of measurement is recommended as it is more feasible in children. No difference, which is significant from a screening point of view, exists between the non-cycloplegic and the cycloplegic cylinder value (< 0.25 D). Retinomax diagnoses abnormal astigmatism (> or = 2 D) in a non-cycloplegic refractive screening at preschool ages with 51-84% sensitivity rates and 98-90% specificity rates, depending on the chosen threshold of manifest astigmatism. If 2 D of manifest astigmatism is chosen as a positive test, the positive predictive value of the screening reaches 81-84% and the negative predictive value 91-90% (right eye-left eye).

Age Distribution↗
PubMed2003

Identification of infants with significant refractive error and strabismus in a population screening program using noncycloplegic videorefraction and orthoptic examination.

PURPOSE: The second Cambridge Infant Vision Screening Program examined whether screening for accommodative errors by using videorefraction without cycloplegia could effectively serve as a first stage of screening for refractive errors, measured by standard cycloplegic retinoscopy. The screening also included an orthoptic examination for detection of strabismus. METHODS: All infants born in the Cambridge (UK) Health District, over a 2-year period, were invited for screening. Of those 5142 (76%) with mean age 8.1 +/- 0.8 months (SD) attended and received noncycloplegic videorefraction and an orthoptic examination. All those with a focusing error or orthoptic problem, as well as a randomly selected sample of visually normal control subjects, were invited to follow-up a month later for cycloplegic retinoscopy, repeat noncycloplegic videorefraction and orthoptic examination. RESULTS: Of the 5142 screened, 514 had a focusing error or orthoptic problem (positives). Four hundred thirty-nine of these and 284 visually normal control subjects (negatives) attended follow-up. A refractive or orthoptic condition was confirmed in 59.0% of the positive cases, whereas infants in 96.8% of the negative cases were confirmed normal. Adjusting for the proportions of the population represented by those infants seen at follow-up, sensitivity for the screening procedure was calculated at 0.67 and specificity at 0.96. Detailed results are presented in terms of the different conditions detected at screening (far, near, and anisometropic focus and orthoptic error), distribution of greatest axes at screening, and a comparison of initial videorefraction with repeat videorefraction and cycloplegic retinoscopy. CONCLUSIONS: A noncycloplegic screening procedure, simpler to perform than cycloplegic screening, succeeded in detecting a large proportion of infants with significant ametropia, particularly those with significant hyperopia, which is considered to be a strabismogenic and amblyogenic risk factor.

Accommodation, Ocular↗
PubMed2003

Refractive error and visual impairment in African children in South Africa.

PURPOSE: To assess the prevalence of refractive error and visual impairment in school-aged African children in South Africa. METHODS: Random selection of geographically defined clusters was used to identify a sample of children 5 to 15 years of age in the Durban area. From January to August 2002, children in 35 clusters were enumerated through a door-to-door survey and examined in temporary facilities. The examination included visual acuity measurements, ocular motility evaluation, retinoscopy and autorefraction under cycloplegia, and examination of the anterior segment, media, and fundus. In nine clusters, children with reduced vision and a sample of those with normal vision underwent independent replicate examinations for quality assurance. RESULTS: A total of 5599 children living in 2712 households were enumerated, and 4890 (87.3%) were examined. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye was 1.4%, 1.2%, and 0.32%, respectively. Refractive error was the cause in 63.6% of the 191 eyes with reduced vision, amblyopia in 7.3%, retinal disorders in 9.9%, corneal opacity in 3.7%, other causes in 3.1%, and unexplained causes in the remaining 12.0%. Exterior and anterior segment abnormalities were observed in 528 (10.8%) children, mainly corneal and conjunctival. Myopia (at least -0.50 D) in one or both eyes was present in 2.9% of children when measured with retinoscopy and in 4.0% measured with autorefraction. Beginning with an upward trend at age 14, myopia prevalence with autorefraction reached 9.6% at age 15. Myopia was also associated with increased parental education. Hyperopia (+2.00 D or more) in at least one eye was present in 1.8% of children when measured with retinoscopy and in 2.6% measured with autorefraction, with no significant predictors of hyperopia risk. CONCLUSIONS: The prevalence of reduced vision is low in school-age African children, most of it because of uncorrected refractive error. The high prevalence of corneal and other anterior segment abnormalities is a reflection of the inadequacy of primary eye care services in this area.

Adolescent↗
PubMedDate not supplied

Evaluation of a hand-held autorefractor in children younger than 6.

PURPOSE: To evaluate a hand-held portable autorefractor in a pediatric population and compare results with those found on retinoscopy by experienced pediatric retinoscopists. METHODS: One-hundred and two children aged 5 to 72 months were examined with and without cycloplegia using an autorefractor, and the results compared with those found on standard retinoscopy by two ophthalmologists masked as to the autorefractor findings. Results were converted from conventional notation using plus cylinder to the h-space notation and compared in three-dimensional h-space. RESULTS: There was remarkable agreement between the results found by autorefraction and manual retinoscopy using loose lenses or a phoropter. The findings were similar both for sphere and cylinder across the age ranges studied. CONCLUSIONS: The Nikon Retinomax is an accurate instrument to estimate refractive error in children younger than 6 and could prove useful in the office, the operating room, or as a screening device.

Child↗
PubMedDate not supplied

Repeatability and validity of astigmatism measurements.

BACKGROUND: As more patients inquire about refractive surgical procedures, the measurement of astigmatism prior to surgery becomes more important in assessing refractive outcome. Knowledge of the repeatability of the astigmatism measurement allows one to distinguish a true change in cylinder power from measurement error. METHODS: Forty adults with structurally normal eyes and refractive errors were evaluated for the repeatability of astigmatic refractive error measures. Noncycloplegic and cycloplegic measurements of refractive astigmatism were made by retinoscopy, subjective refraction, and autorefraction. All measures were made at 2 visits within 2 weeks by the same examiner. Difference versus mean plots and the 95% limits of agreement of each technique determined the repeatability of a measurement and the agreement between the methods of measurement. RESULTS: The most reliable measure of astigmatic refractive error was cycloplegic autorefraction, with 95% limits of agreement of +/- 0.28 D, followed by noncycloplegic autorefraction (+/- 0.35 D) and cycloplegic subjective refraction (+/- 0.44 D). Noncycloplegic retinoscopy was the least reliable astigmatic refractive error measure, with interoccasion 95% limits of agreement of +/- 1.02 D. The most repeatable measurement of cylinder axis was cycloplegic autorefraction; none of the measurements differed by 10 degrees or more. The least repeatable measurement was noncycloplegic retinoscopy; 40% of the measurements differed by 10 degrees or more. CONCLUSION: For studies seeking to measure changes in astigmatism in normal eyes, cycloplegic autorefraction is the method of choice.

Adult↗
PubMed2000

Screening for refractive errors with the Topcon PR2000 Pediatric Refractometer.

PURPOSE: The PR2000 (Topcon, Tokyo, Japan) is a photorefractor that has been used in a population study comparing different methods of screening preschool children. The present study was conducted to determine the accuracy of the device in a largely clinical population. METHODS: Two hundred twenty-two children less than 8 years of age were included. All children were examined by an orthoptist using the PR2000 without inducing cycloplegia. All children then underwent retinoscopy with cycloplegia by an examiner who was unaware of the results from the PR2000 examination. RESULTS: The PR2000 gave a numerical reading for 90% of the children's right eyes and the message "Out of range" for a further 5%. The readings underestimated the amount of hypermetropic or astigmatic refractive error found on retinoscopy by an amount proportional to the magnitude of the refractive error. Agreement with retinoscopy for the axis of astigmatism more than 0.75 D was moderately good (intraclass correlation coefficient [ICC] = 0.63). The PR2000 was more useful as a screener, especially for anisometropia for which it was 91% sensitive and 92% specific. The repeatability was good for sphere (ICC = 0.74), less so for astigmatism (ICC = 0.59), and better than the optometrist for anisometropia (ICC = 0.38). The presence of nonrefractive diagnoses and the age of the children examined made little difference in the screening results. CONCLUSIONS: The PR2000 underestimated hypermetropic refractive errors when used without cycloplegia. However, it was at least as good a screening device as other similar instruments, especially when judged by its ability to detect anisometropia and the repeatability of the results.

Child↗
PubMed1998

[A research on clinical values of corneal topography and keratometer in measuring astigmatism].

OBJECTIVE: To compare the accuracy of corneal topography, keratometer and cycloplegic retinoscopy in measuring astigmatism for refractive surgery. METHODS: Three hundred and sixty eyes with ametropia were randomly selected. The results of corneal topography, that of keratometer and cycloplegic retinoscopy in measuring astigmatism before refractive surgery were compared, and the measuring results of corneal topography and that of keratometer for 72 eyes after photorefractive keratectomy (PRK) and 95 eyes after laser in situ keratomileusis (LASIK) were also compared. RESULTS: No significant difference was found in axes of astigmatism among the three groups. As for diopters of astigmatism, there was no significant difference between the group of corneal topography (DeltaSim K) and the group of keratometer (DeltaK), but we found significant difference between the group of cycloplegic retinoscopy and the other two groups before and after refractive surgery. Significant difference was also found between DeltaSimK and DeltaK after PRK and LASIK. CONCLUSIONS: Our investigation demonstrates that before refractive surgery the keratometer has a similar clinical value as that of corneal topography, and the DeltaSim K value is related to the graphic pattern of corneal topography. However, keratometer is limited in measuring mild changes in corneal curvature after refractive surgery, while the astigmatism expressed by DeltaSim K in corneal topography is more accurate.

Adolescent↗
PubMed2003

A myopic shift in Australian Aboriginals: 1977-2000.

BACKGROUND/AIMS: The prevalence of myopia has been reported to have increased in a number of population groups. We compared the refraction of Australian Aboriginal adults in 2000 with data collected in 1977 to assess whether there had been a change in the prevalence of myopia. METHOD: Australian Aboriginal adults aged 20 to 30 years old were selected from Central Australian communities in 2000. Refraction was determined by noncycloplegic autorefraction. This was compared to mydriatic retinoscopy data collected in 1977. "Observer trials" were undertaken to assess the comparability of noncycloplegic autorefraction measurements and cycloplegic retinoscopy. Spherical equivalence cylinder and spheric were determined for all right and left eyes and compared using an analysis of variance. RESULTS: A total of 128 adults (58 males, 70 females) were examined in 2000 and compared with 161 adults (107 males, 54 females) examined in 1977. The mean spherical equivalent in 2000 was -0.55 D +/- 0.88 D and in 1977 was +0.54 D +/- 0.81 D. The difference of -1.09 D was highly significant (F = 126, P < .001). Intraclass correlation coefficients showed good agreement between noncycloplegic autorefraction and cycloplegic retinoscopy. Neither gender, schooling, nor diabetes was associated with an increased risk of myopia. CONCLUSIONS: There appears to have been a significant shift toward myopia in Australian Aboriginals between 1977 and 2000. The cause of this myopic shift is unknown but mirrors that observed in other populations in recent years.

Adult↗
PubMed1991

Variation and correlation of clinical tests of accommodative function in a sample of school-age children.

Accommodative facility, lag of accommodation, accommodative response, and relative accommodation were measured in 244 school-age (7.9 to 15.9 years of age) children. The tests studied included monocular estimate method (MEM) dynamic retinoscopy, Nott dynamic retinoscopy, low neutral dynamic retinoscopy, the binocular cross cylinder test, lens accommodative rock (facility), distance (near-far) accommodative rock, negative relative accommodation (NRA), and positive relative accommodation (PRA). The mean, standard deviation, and range of test findings of each test are presented. Coefficients of correlation among the various tests are presented.

Accommodation, Ocular↗
PubMed1997

Effect of contralateral fog during refractive error assessment.

BACKGROUND: When assessing refractive error using static retinoscopy, it is conventional to fog the contralateral eye by approximately 2.00 D to prevent a blur-driven accommodative response stimulating consensual accommodation in the tested eye. However, the effect of higher amounts of contralateral fog (e.g., in a moderate-to-high uncorrected myopic individual) during refractive error assessment is unclear. METHODS: We assessed the refractive state in 16 visually normal myopic subjects while fogging the contralateral eye between zero and 6.00 D, in 1.00 D increments. Retinoscopy was simulated by shining a streak retinoscope light into the right eye, while simultaneously measuring the refractive state of this eye objectively. RESULTS: No significant change in mean refractive state was observed for up to 5.00 D of contralateral fog. But, 6.00 D of contralateral fog produced a significant mean increase in the myopic direction of 0.13 D. Also, in three subjects, a myopic shift of approximately 0.60 D was recorded after the introduction of 6.00 D of contralateral fog. Nevertheless, the magnitude of these largest shifts in refractive error are still smaller than the previously reported degree of repeatability of static retinoscopy. CONCLUSIONS: Since large amounts of contralateral fog produced only small and clinically insignificant changes in the refractive state, the practitioner merely needs to ensure that the nontested eye is indeed fogged. The magnitude of fog present will have only a minimal effect on the final result.

Adult↗
PubMed1996

The importance of the corneal epithelium in excimer-laser photorefractive keratectomy.

To evaluate the importance of the epithelium for postoperative regression we undertook excimer-laser photoreactive keratectomy (PRK) in six rabbits. After the epithelium had been removed mechanically, two rabbits underwent a -3.0 D procedure; two rabbits, a -6.0 D procedure; and two rabbits, a -9.0 D procedure. Refraction was monitored pre- and postoperatively using streak retinoscopy. Rabbits were killed at 3 weeks after PRK and the thickness of the corneal epithelium in the centre of the ablation zone and in an untreated area just outside the treatment zone was measured using light microscopy. At the time of killing, no stromal haze was visible on slit-lamp biomicroscopy. In all rabbits the thickness of the corneal epithelium over the untreated area was between 31.4 and 36.7 microns. In contrast, the thickness of the epithelium in the centre of the ablation zone in rabbits treated with a -3.0 D procedure was only slightly increased, and retinoscopy showed a change in refraction of around 3 D. All other rabbits showed a significant increase in epithelial thickness, whereas the amount of thickness correlated with the amount of myopic regression. One rabbit in the -6.0 D group showed an increase in epithelial thickness of 18.4 microns and a myopic regression of 1.5 D. In both rabbits in the -9.0 D group the amount of corneal tissue removed by the laser was nearly completely substituted by epithelial hyperplasia. Postoperative retinoscopy showed nearly the same refraction as had been obtained preoperatively. In summary, the postoperative control of epithelial thickness seems to be an important factor for the success of excimer-laser PRK and, in particular, for high degrees of myopia.

Animals↗