1
|
Abstract
SIGNIFICANCE The article highlights various topographic patterns and their prevalence in a large spectrum of ectatic corneal diseases (ECDs). Knowledge of these patterns can help clinicians for quicker diagnosis and selection of appropriate contact lens design. PURPOSE This study aimed to determine various corneal topography patterns and their prevalence in patients with ECDs who visited a tertiary eye hospital in western India. METHODS Keratoconus, pellucid marginal degeneration, keratoglobus, and post-refractive surgery progressive corneal ectasia are considered under ECDs. This cross-sectional retrospective study reviewed records of 632 consecutive patients with clinical ECDs at their first presentation. The right eye was considered for pattern analysis. In cases with suspected or forme fruste ectasia in the right eye, the fellow eye was considered. A sagittal map with standard scale of Atlas 9000 topographer (Carl Zeiss Meditec AG, Jena, Germany) was used for pattern analysis. They were classified into 18 categories and grouped under five groups. The prevalence of these patterns was calculated and assessed with 95% confidence interval (CI). RESULTS The mean ± SD age of patients was 23.6 ± 8.2 years. The highest prevalence was of asymmetric patterns (39.6% [95% CI, 35.7 to 43.5%]; asymmetric bowtie [AB] with steepest radial axis index [SRAX], 18.8%; AB with inferior steep, 16.0%; AB with superior steep [SS], 3.2%; symmetric bowtie with SRAX, 1.6%) and of central or paracentral patterns (28.6% [95% CI, 25.1 to 32.3%]; inferior steep, 12.2%; heart, 7.4%; oval, 4.1%; symmetric bowtie, 2.4%; round, 1.6%; irregular, 0.9%) followed by advanced patterns (17.3% [95% CI, 14.4 to 20.4%; nonmeasurable, 5.4%; globus, 4.9%; indiscriminate, 7.0%). The peripheral patterns were 11.7% (95% CI, 9.3 to 14.4%) (claw, 6.3%; junctional, 3.2%; butterfly, 1.9%; SS, 0.3%). Rare patterns were 2.8% (95% CI, 1.7 to 4.5%) (superior [junctional, claw, and heart], AB with SS with SRAX, and AB with SRAX located temporally). CONCLUSIONS Asymmetric and central or paracentral are the most common patterns in our study. The higher prevalence of advanced patterns indicates the need for earlier diagnosis of ECDs in our population. The peripheral patterns also have significant prevalence.
Collapse
|
2
|
Kataoka T, Nishida T, Murata A, Ito M, Isogai N, Horai R, Kojima T, Yoshida Y, Nakamura T. Control-matched comparison of refractive and visual outcomes between small incision lenticule extraction and femtosecond laser-assisted LASIK. Clin Ophthalmol 2018; 12:865-873. [PMID: 29785082 PMCID: PMC5953304 DOI: 10.2147/opth.s161883] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Purpose This retrospective case-matched study aimed to compare visual and refractive outcomes between small incision lenticule extraction (SMILE) and LASIK. Patients and methods Patients who underwent SMILE (34 eyes of 23 patients) or LASIK (34 eyes of 24 patients) were enrolled and matched according to preoperative manifest refractive spherical equivalents. The mean preoperative manifest refractive spherical equivalent was −4.69±0.6 and −4.67±0.64 D in the SMILE and LASIK groups, respectively. The safety, efficacy, and predictability were compared 3 months after surgery. Changes in corneal refractive power from the center to peripheral points and their maintenance ratios were analyzed and compared between the two groups. Results In the SMILE and LASIK groups, 82.4% and 85.3% of patients, respectively, achieved 20/13 or better uncorrected distance visual acuity (p=1.00). There were no eyes that lost two or more lines of corrected distance visual acuity in either group. The maintenance ratios of corneal refractive power changes at the peripheral points in the SMILE group were significantly higher than those in the LASIK group (p<0.05). Conclusion Both groups achieved similar high efficacy and safety. SMILE surgery resulted in higher refractive power correction in the peripheral cornea than LASIK surgery.
Collapse
Affiliation(s)
| | | | | | | | | | | | - Takashi Kojima
- Nagoya Eye Clinic, Nagoya, Japan.,Department of Ophthalmology, Keio University School of Medicine, Tokyo, Japan
| | | | | |
Collapse
|
3
|
Randleman JB. Remembering George O. Waring, III. J Refract Surg 2015; 31:218-21. [DOI: 10.3928/1081597x-20150319-01] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
|
4
|
Abstract
The shape of a cornea, as measured by corneal topography, can be influenced by a variety of factors. Direct and obvious influences on corneal shape include corneal pathology, corneal surgery, and contact lenses. With the modern and widespread use of computerized videokeratoscopy, subtle topographic changes from other external and systemic influences can now be detailed. The purpose of this review is to examine ocular surface influences and indirect surgical, pathological, and pharmacological factors that affect the corneal shape and acquired topographic maps. The clinical consequences of altered corneal topography will be highlighted throughout.
Collapse
Affiliation(s)
- Loretta Szczotka-Flynn
- Department of Ophthalmology, University Hospitals of Cleveland and Case Western Reserve University, Cleveland, Ohio 44106, USA.
| |
Collapse
|
5
|
Wang IJ, Sun YC, Lee YC, Hou YC, Hu FR. The relationship between anterior corneal aberrations and contrast sensitivity in conventional LASIK. Curr Eye Res 2006; 31:563-8. [PMID: 16877264 DOI: 10.1080/02713680600814761] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
PURPOSE To evaluate the changes of anterior corneal aberrations before and after laser in situ keratomileusis (LASIK) and to assess the correlation between contrast sensitivity and anterior corneal aberrations. METHODS Right eyes of 51 patients including 6 males and 45 females undergoing conventional LASIK from September 2000 to July 2003 were enrolled. The calculation of anterior corneal aberrations before and after LASIK was obtained by analyzing the corneal topography from TMS-1 by using VOL-CT Version 6.23 software. Contrast sensitivity was measured after LASIK with an MCT 8000 under daytime and nighttime settings and with glare conditions. The differences of the Zernike coefficients and root mean square (RMS) of anterior corneal aberrations before and after LASIK were analyzed. The changes of contrast sensitivity at 1.5, 3, 6, 12, and 18 cpd were added separately for daytime and nighttime contrast sensitivity with and without glare after LASIK and were correlated with the changes of anterior corneal aberrations. RESULTS Vertical coma, RMS of coma-like RMS of spherical-like, RMS of trefoil-like and RMS of higher-order anterior corneal aberrations increased significantly after LASIK surgery. There were no significant correlations between the changes of anterior corneal aberrations and the changes of contrast sensitivity at daytime and nighttime, with and without glare. Contrast sensitivity at daytime and nighttime decreased at each spatial frequency after LASIK. CONCLUSIONS LASIK surgery induces changes of the anterior corneal aberrations. However, changes in anterior corneal aberrations did not correlate with the changes of contrast sensitivity at daytime and nighttime, with and without glare.
Collapse
Affiliation(s)
- I-Jong Wang
- Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan.
| | | | | | | | | |
Collapse
|
6
|
Oshika T, Okamoto C, Samejima T, Tokunaga T, Miyata K. Contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes. Ophthalmology 2006; 113:1807-12. [PMID: 16876865 DOI: 10.1016/j.ophtha.2006.03.061] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 03/23/2006] [Accepted: 03/23/2006] [Indexed: 11/16/2022] Open
Abstract
PURPOSE To investigate the relation between contrast sensitivity function and ocular higher-order wavefront aberrations in normal human eyes. STUDY DESIGN Prospective observational case series. PARTICIPANTS Three hundred seven eyes of 161 normal subjects, ranging in age from 15 to 60 years (30.9+/-8.0 [mean +/- standard deviation]). METHODS Ocular higher-order aberrations were measured for a 4-mm pupil using the Hartmann-Shack wavefront analyzer. The root-mean-square of the third- and fourth-order Zernike coefficients was used to represent comalike and spherical-like aberrations, respectively. We measured contrast sensitivity, low-contrast visual acuity (VA), and letter contrast sensitivity. From the contrast sensitivity data, the area under the log contrast sensitivity function (AULCSF) was calculated. Pupil diameter in a photopic condition was recorded using a digital camera. RESULTS Multiple linear regression analysis revealed that comalike aberration (P = 0.002) was significantly associated with AULCSF, but spherical-like aberration (P = 0.200), age (P = 0.185), and photopic pupil diameter (P=0.252) were not. Comalike aberration showed a significant correlation with low-contrast VA (P<0.001), but spherical-like aberration (P = 0.293), age (P = 0.266), and pupil diameter (P = 0.756) did not. Comalike aberration was found to be significantly associated with letter contrast sensitivity (P<0.001), but spherical-like aberration (P=0.082), age (P = 0.370), and pupil diameter (P = 0.160) were not. CONCLUSIONS In normal human eyes, comalike aberration of the eye significantly influences contrast sensitivity function.
Collapse
Affiliation(s)
- Tetsuro Oshika
- Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Tsukuba, Ibaraki, Japan.
| | | | | | | | | |
Collapse
|
7
|
González-Méijome JM, Sañudo-Buitrago F, López-Alemany A, Almeida JB, Parafita MA. Correlations Between Central and Peripheral Changes in Anterior Corneal Topography After Myopic LASIK and Their Implications in Postsurgical Contact Lens Fitting. Eye Contact Lens 2006; 32:197-202. [PMID: 16845266 DOI: 10.1097/01.icl.0000191951.89321.b6] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To investigate the changes in central and peripheral anterior corneal curvatures after myopic laser in situ keratomileusis (LASIK) and to correlate them with the manifest refractive change to discuss how such results could affect post-LASIK corneal topography profiles and midterm stability and their implications in postsurgical contact lens fitting. METHODS Topographic and refractive data from 18 eyes of 11 patients that had undergone myopic LASIK were collected for 6 months after surgery. Short-term and midterm topographic responses were investigated and correlated with spherical equivalent manifest refractive changes. RESULTS There was a strong correlation between eccentricity changes and manifest refractive change 15 days after surgery (r = 0.753, P < 0.001), with no significant changes thereafter for the following 6 months (r = 0.148, P = 0.114). A strong linear relationship was found between baseline manifest refraction and changes in corneal curvature at the center (r = 0.810, P < 0.001), 4-mm chord (r = 0.895, P < 0.001), and 6-mm chord (r = 0.696, P < 0.001). Statistically significant changes were also found after the first 15 days (P < 0.005) and showed a regression effect that affects the three zones. In this case, a weaker relationship was found between curvature regression and the final refractive change for the central location (r = 0.412, P = 0.004), 4-mm chord area (r = 0.430, P = 0.003), and 6-mm chord area (r = 0.283, P = 0.023). CONCLUSIONS.: After myopic LASIK, the anterior corneal dioptric power is expected to change, on average, approximately 77% of the attempted spherical equivalent correction at the center; 60% at the 4-mm chord region, where the stronger correlation between topographic and refractive change is found; and 30% at the 6-mm chord area. The paracentral area 4 mm from the center seems to be more likely to predict baseline corneal curvature from manifest refractive change. Some degree of regression in the midterm period is expected to occur after myopic LASIK, which shows a significant correlation with the manifest refractive change. Again, this effect is more evident and more accurately predicted at the 4-mm chord area. The results of the current study are of interest for those fitting contact lenses after myopic LASIK.
Collapse
Affiliation(s)
- José M González-Méijome
- Department of Physics (Optometry), School of Sciences, University of Minho, Braga, Portugal.
| | | | | | | | | |
Collapse
|
8
|
Barreto J, Netto MV, Cigna A, Bechara S, Kara-José N. Precision of Higher Order Aberration Repeatability With NIDEK OPD-Scan Retinoscopic Aberrometry. J Refract Surg 2006; 22:S1037-40. [PMID: 17444090 DOI: 10.3928/1081-597x-20061102-06] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To evaluate repeatability of the total high order aberrations with a retinoscopic wavefront sensor. METHODS This prospective case series analyzed 12 eyes from 6 patients who underwent wavefront measurement using retinoscopic aberrometry with the NIDEK Optical Path Difference Scan (OPD-Scan). Four consecutive wavefront measurements of each eye were taken by two trained examiners for 5.8+/-0.8-mm and 8.2+/-0.6-mm pupils (P=.002, Wilcoxon test). Total high order aberrations out to the eighth order were assessed including third order coma, third order trefoil, fourth order quadrafoil, fourth order secondary astigmatism, and fourth order spherical aberrations. Differences between measurements of all of the variables were analyzed. A P value <.05 was considered statistically significant. RESULTS Repeatability analysis of the root-mean-square of total higher order aberrations, coma, trefoil, quadrafoil, secondary astigmatism, and spherical aberrations for both dilated and nondilated pupils did not show a statistically significant difference among all repeated measurements, except for trefoil and secondary astigmatism (analysis of variance and the Friedman test). The repeatability of total higher order aberrations was 0.15 microm for nondilated pupils and 0.18 microm for dilated pupils. Except for trefoil measurements, all high order aberrations showed reproducibility >0.15 microm when Zernike coefficients were analyzed individually. CONCLUSIONS The NIDEK OPD-Scan aberrometer measures total higher order astigmatism and most individual aberrations with acceptable repeatability. However, measurement of trefoil with this instrument is less repeatable.
Collapse
Affiliation(s)
- Jackson Barreto
- Department of Ophthalmology, University of São Paulo, Brazil
| | | | | | | | | |
Collapse
|
9
|
Donate D, Denis P, Burillon C. Étude prospective de la sensibilité au contraste et des effets visuels après LASIK. J Fr Ophtalmol 2005; 28:1070-5. [PMID: 16395199 DOI: 10.1016/s0181-5512(05)81140-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
PURPOSE To evaluate changes in visual effects (contrast sensitivity, halos, and glare) following laser in situ keratomilleusis (LASIK). PATIENTS AND METHODS In this prospective study, 72 eyes had LASIK to correct myopia. Contrast sensitivity was tested preoperatively, as well as 6 and 12 months postoperatively. The spatial frequencies tested were 3, 6, 12, and 18 cycles per degree (c/d). There were two groups: group 1 for myopia between -6 D (n=30) and -7.5 D and group 2 for myopia between -7.5 D and -10 D (n=25). There were 17 cases with loss of sight. For each visit, pupil diameter, halos, and glare were measured. RESULTS Contrast sensitivity was better in group 1 than in group 2 (p<0.05) (for spatial frequencies of 3, 12, 18, c/d). In group 1, contrast sensitivity decreased 6 months postoperatively for all spatial frequencies (p<0.05); 12 months after surgery the changes were not significant. In group 2, changes were not significant. For halos and glare, pre- and postoperative percentages were not different. There was no correlation with pupil diameter. CONCLUSIONS After LASIK to correct myopia, there may be a persistent decrease in contrast sensitivity. Changes are only significant at 6 months postoperatively. Patients should be informed preoperatively of this possible decrease in functional vision.
Collapse
Affiliation(s)
- D Donate
- Service d'Ophtalmologie, Pavillon C, Hôpital Edouard Herriot, 5, place d'Arsonval, 69003 Lyon.
| | | | | |
Collapse
|
10
|
Szczotka-Flynn L, Jani BR. Comparison of Axial and Tangential Topographic Algorithms for Contact Lens Fitting After LASIK. Eye Contact Lens 2005; 31:257-62. [PMID: 16284504 DOI: 10.1097/01.icl.0000161707.83797.87] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE Computerized videokeratography (CVK) has become the standard method for measuring the corneal curvature after refractive surgery. However, few resources exist on the use of CVK data for postoperative contact lens fitting, and no recommendations exist on the selection of the best topographic algorithm relevant to gas-permeable (GP) lens fitting. This study assessed the optimal use of topographic data to fit spherical GP contact lenses on patients who have undergone laser in situ keratomileusis. METHODS A retrospective analysis of CVK maps from eight post-LASIK eyes fitted with spherical GP lenses was performed in the Contact Lens Service of the Department of Ophthalmology at Case Western Reserve University and University Hospitals of Cleveland. Axial and tangential maps from the Dicon CT 200 (version 3.50) or Humphrey Atlas (version A8) topographer were analyzed. Averaged dioptric curvatures from different locations (inferior, superior, and temporal) at various distances (2.0 mm, 2.5 mm, 3.0 mm, 3.5 mm, and 4.0 mm) from the vertex normal of each eye were compared with the base curves of the prescribed GP contact lenses. RESULTS One-way analysis of variance, Pearson correlation analysis, and paired t tests showed that the best topographic predictors of a successful GP base curve were the average curvatures at the 4.0 mm distance on the axial maps (r=0.8078, P=0.05) and at the 2.0 mm distance on the tangential maps (r=0.9738, P=0.0002). The mean dioptric powers of the GP base curve, axial map 4.0 mm curvature, and tangential map 2.0 mm curvature were 41.50 diopters (D), 42.65 D, and 42.67 D, respectively. CONCLUSION To simplify and guide GP fitting after LASIK, the average dioptric curvature 4.0 mm from the vertex normal on axial maps or 2.0 mm from the vertex normal on tangential maps are the best predictors of accurate GP base curve selection.
Collapse
Affiliation(s)
- Loretta Szczotka-Flynn
- Department of Ophthalmology, University Hospital of Cleveland, Cleveland, OH 44106, USA.
| | | |
Collapse
|
11
|
Pérez-Carrasco MJ, Puell MC, Sánchez-Ramos C, López-Castro A, Langa A. Effect of a Yellow Filter on Contrast Sensitivity and Disability Glare After Laser in situ Keratomileusis Under Mesopic and Photopic Conditions. J Refract Surg 2005; 21:158-65. [PMID: 15796221 DOI: 10.3928/1081-597x-20050301-11] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To analyze the effect of a yellow filter on contrast sensitivity and disability glare under mesopic and photopic luminance conditions in laser in situ keratomileusis (LASIK) patients and control subjects. METHODS Contrast sensitivity with and without glare was determined in 27 patients who had undergone LASIK at least 1 year previously and in 30 control subjects. Tests were performed with and without a coated yellow filter (X-482 nm cut-off) using the Mesotest II or Mesoptometer II (Oculus, Wetzlar, Germany) under mesopic conditions, and the Contrast Glaretester 1000 (Takagi, Seiko Co Ltd, Nagano, Japan) under photopic conditions. RESULTS Under mesopic conditions, log contrast sensitivity without glare decreased by 0.14 log units in the LASIK group. When the yellow filter was used, this variable showed a significant increase of 0.04 log units and the proportion of patients able to discriminate the mesopic contrast limit of 1:5 rose from 70% to 78%. With glare, the yellow filter also improved contrast sensitivity in LASIK patients, but not significantly. Under photopic conditions, no statistical differences were observed between results obtained with and without the yellow filter in the LASIK group or between the LASIK and control group without glare. CONCLUSIONS Mesopic contrast sensitivity without glare was worse in LASIK patients and increased significantly with the yellow filter. The filter had no effect under photopic conditions. No disability glare differences were noted between the LASIK and control groups or between the LASIK without and with filter groups under mesopic and photopic conditions.
Collapse
|
12
|
Pan Q, Gu YS, Wang J, Sheng Y, Du CX, Huang ZM, Xin SH. Differences between Regressive Eyes and Non-Regressive Eyes after LASIK for Myopia in the Time Course of Corneal Changes Assessed with the Orbscan. Ophthalmologica 2004; 218:96-101. [PMID: 15004497 DOI: 10.1159/000076143] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2003] [Accepted: 09/25/2003] [Indexed: 11/19/2022]
Abstract
The aim of this study was to compare regressive eyes with non-regressive eyes after laser in situ keratomileusis (LASIK) for myopia with regard to the time course of biomechanical changes of the cornea and to evaluate the possible roles of these changes in refractive regression following surgery. 15 eyes of 9 patients with refractive regression and 15 eyes of 11 patients with no refractive regression after LASIK for myopia were enrolled in this study. The time courses of central corneal thickness (CCT) and anterior/posterior corneal curvature radiuses (CCR) were measured with Orbscan slit scanning before and 1 week, 1 month and 3 months after LASIK for myopia. The regressive and non-regressive eyes had similar time courses of CCT before and after LASIK, whereas the 2 groups differed in the time courses of corneal shifting movements. In the regression group, the posterior CCR after LASIK was relatively stable (all p > 0.05). By contrast, in the non-regression group, the postoperative posterior CCR at week 1 had a significantly steeper curvature than that at month 3 (p = 0.000). The anterior CCR in the regression group at week 1 had a significantly flatter curvature than that at month 3 (p = 0.002) postoperatively. In contrast, there was no significant change of anterior CCR postoperatively (all p > 0.05) in the non-regression group. Taken together, these data suggest that refractive regression after LASIK might be mainly induced by corneal protrusion rather than central corneal thickening.
Collapse
Affiliation(s)
- Qing Pan
- Department of Ophthalmology, Medical College of Zhejiang University, Hangzhou, People's Republic of China
| | | | | | | | | | | | | |
Collapse
|
13
|
Pesudovs K, Hazel CA, Doran RML, Elliott DB. The usefulness of Vistech and FACT contrast sensitivity charts for cataract and refractive surgery outcomes research. Br J Ophthalmol 2004; 88:11-6. [PMID: 14693761 PMCID: PMC1771933 DOI: 10.1136/bjo.88.1.11] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
AIM To investigate the repeatability and sensitivity of two commonly used sine wave patch charts for contrast sensitivity (CS) measurement in cataract and refractive surgery outcomes. METHODS The Vistech CS chart and its descendant, the Functional Acuity Contrast Test (FACT), were administered in three experiments: (1) Post-LASIK and age matched normal subjects; (2) Preoperative cataract surgery and age matched normal subjects; (3) Test-retest repeatability data in normal subjects. RESULTS Contrast sensitivity was similar between post-LASIK and control groups and between the Vistech and FACT charts. The percentage of subjects one month post-LASIK achieving the maximum score across spatial frequencies (1.5, 3, 6, 12, 18 cycles per degree) were (50, 33, 13, 13, 0 respectively) for FACT, but only (0, 0, 13, 4, 0 respectively) for Vistech. A small number of cataract patients also registered the maximum score on the FACT, but up to 60% did not achieve the minimum score. Test-retest intraclass correlation coefficients varied from 0.28 to 0.64 for Vistech and 0.18 to 0.45 for FACT. Bland-Altman limits of agreement across spatial frequencies were between +/-0.30 and +/-0.85 logCS for Vistech, and +/-0.30 to +/-0.75 logCS for FACT. DISCUSSION The Vistech was confirmed as providing poorly repeatable data. The FACT chart, likely because of a smaller step size, showed slightly better retest agreement. However, the reduced range of scores on the chart due to the smaller step size led to ceiling (post-LASIK) and floor (cataract) effects. These problems could mask subtle differences between groups of patients with near normal visual function as found post-refractive or cataract surgery. The Vistech and FACT CS charts are ill suited for refractive or cataract surgery outcomes research.
Collapse
Affiliation(s)
- K Pesudovs
- Department of Optometry, University of Bradford, Richmond Road, Bradford BD7 1DP, UK.
| | | | | | | |
Collapse
|
14
|
Cua IY, Pepose JS. Proper Positioning of the Plume Evacuator in the VISX Star3 Excimer Laser Minimizes Central Island Formation in Patients Undergoing Laser in situ Keratomileusis. J Refract Surg 2003; 19:309-15. [PMID: 12777026 DOI: 10.3928/1081-597x-20030501-07] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To identify risk factors in a series of patients who developed steep central islands after laser in situ keratomileusis (LASIK). METHODS We analyzed and compared the refractive and topographic outcome of a study group composed of 83 eyes of 44 patients who underwent LASIK using the VISX Star3 excimer laser with a refraction-matched control group of 83 eyes treated later. The vacuum aspirator of the excimer laser was abnormally positioned during the surgeries performed in the study group. RESULTS Mean preoperative spherical equivalent refraction in the study group was -6.75 +/- 2.50 D. Four eyes with a mean preoperative spherical equivalent refraction of -9.27 +/- 2.29 D developed steep central islands. Thirty-three (38%) of 83 eyes treated needed retreatment for residual myopia or myopic astigmatism. In the control group, mean preoperative spherical equivalent refraction was -6.76 +/- 2.50 D. Ninety-three percent of eyes were within +/- 1.00 D of target refraction. Five (6.02%) of 83 eyes required retreatment and no eyes developed central islands. CONCLUSION The abnormally positioned vacuum aspirator coupled with the higher preoperative refractive correction were the likely causative factors for central island formation and the increased incidence of undercorrection in these patients.
Collapse
Affiliation(s)
- Irwin Y Cua
- Pepose Vision Institute, Chesterfield, MO 63017, USA
| | | |
Collapse
|
15
|
Abstract
Although laser in situ keratomileusis (LASIK) enjoys a high success rate, postoperative residual or induced astigmatism may limit uncorrected visual acuity and cause starbursts and glare at night. Irregular astigmatism can also cause loss of best-corrected visual acuity, monocular diplopia, and ghosting of images. Astigmatism may be measured by keratometry and refraction, while corneal topographic techniques help to define irregular astigmatism, in particular. Further information may be obtained regarding induced higher-order aberrations with aberrometry. Because astigmatism has both direction and magnitude, its analysis is more complex than that of the spherical component of the treatment. There are multiple approaches to the analysis of surgically induced astigmatism, including vector analysis, conversion to a Cartesian coordinate system, matrix formalism, and linear optics. Both excimer laser and incisional techniques may be used to correct astigmatism after LASIK, but the treatment of irregular astigmatism requires selective zonal ablation techniques or customized corneal ablations, using topographic or wavefront derived data.
Collapse
Affiliation(s)
- Helen K Wu
- Tufts University School of Medicine, New England Eye Center, Boston Massachusetts 02111, USA.
| |
Collapse
|
16
|
Abstract
PURPOSE Some case reports have shown that abnormal focal steepening of the cornea appears to cause monocular diplopia by prismatic effect. The purpose of this study was to ascertain prospectively if the pattern of corneal distortion was related specifically to persistent monocular diplopia. METHODS We selected 16 visually normal eyes (controls) and two groups of volunteers in which abnormal focal steepening of the cornea was expected to be found: 40 eyes of 20 volunteers who wore rigid gas-permeable contact lenses (RGP) for myopia and 10 eyes of seven patients with keratoconus. New charts that consisted of white dials on a black background were prepared for detection and measurement of secondary images. Any secondary image that could not be eliminated by any trial lens correction was defined as a persistent secondary image, using the charts. Corneal topography from all subjects was classified: round or oval, symmetric or asymmetric bowtie, abnormal focal steepening accompanied by contact lens-induced corneal warpage or keratoconus, or amorphous. We analyzed the relationship between the persistent secondary image and the corneal topographical patterns. RESULTS A persistent secondary image was detected from seven eyes of RGP wearers and all keratoconus eyes. All corneal topographies of the seven RGP eyes with a persistent secondary image showed abnormal focal steepening related to contact lens-induced corneal warpage. The direction of the persistent secondary image was approximately consistent with the location of the focal steepening as seen on the corneal topography. CONCLUSION Abnormal focal steepening of the cornea that appeared to produce a prismatic difference between two parts of the cornea was specifically related to persistent monocular diplopia.
Collapse
Affiliation(s)
- Kazuo Takei
- Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Japan.
| |
Collapse
|
17
|
Takei K, Sano Y, Achiron LR, Carr JD, Stulting RD, Thompson KP, Waring GO. Monocular Diplopia Related to Asymmetric Corneal Topography After Laser in situ Keratomileusis. J Refract Surg 2001; 17:652-7. [PMID: 11758983 DOI: 10.3928/1081-597x-20011101-04] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
PURPOSE To show a specific relationship between monocular diplopia and corneal refractive asymmetry after laser in situ keratomileusis (LASIK). METHODS One hundred thirty-eight eyes of 98 patients who underwent LASIK for myopia between -2.12 and -17.75 D were examined under room-lighted conditions. We examined 51 eyes at 2 weeks, 46 eyes at 3 months, 32 eyes at 6 months, and 9 eyes at 1 year after LASIK. We attempted to correlate the presence of monocular diplopia with their corneal topographical features. RESULTS Eight eyes of five patients (five eyes at 2 weeks, three eyes at 3 months after LASIK) produced symptoms of monocular diplopia. These symptomatic patients had a common corneal topographical feature caused by decentralized or inhomogeneous ablation. Every pupillary area in the patients' topographies contained steeper and flatter areas. The range of refractive power variation in these asymmetric areas was at least 1.50 D. The location of the secondary image correlated with the direction of the steeper area in all eight eyes. Pinhole viewing eliminated or reduced the prominence of secondary images in every case. CONCLUSION Monocular diplopia following LASIK appears to correlate with postoperative corneal refractive power variation inside the pupillary area, caused by decentralized or inhomogeneous ablation.
Collapse
Affiliation(s)
- K Takei
- Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.
| | | | | | | | | | | | | |
Collapse
|
18
|
Nakamura K, Bissen-Miyajima H, Toda I, Hori Y, Tsubota K. Effect of laser in situ keratomileusis correction on contrast visual acuity. J Cataract Refract Surg 2001; 27:357-61. [PMID: 11255045 DOI: 10.1016/s0886-3350(00)00745-8] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
PURPOSE To evaluate the changes in contrast visual acuity (CVA) based on the amount of myopic correction with laser in situ keratomileusis (LASIK). METHODS In this prospective study, patients with myopia ranging from -2.0 to -14.0 diopters (D) were divided into 2 groups: those with myopia less than -6.0 D (n = 20) and those with myopia greater than -6.0 D (n = 13). The CVA was measured preoperatively and 1 week and 1 and 3 months postoperatively using Variable Contrast Visual Acuity Charts. RESULTS The patients with less than -6.0 D of myopia had a CVA decrease of 15% 1 week postoperatively, which recovered by 1 month, and a decrease of 2.5% 1 week and 1 month postoperatively, which recovered by 3 months. The patients with more than -6.0 D of myopia had a decrease of 15% and 2.5% at all postoperative times. CONCLUSIONS After LASIK to correct myopia of greater than -6.0 D, there may be a persistent decrease in intermediate and low CVA. Patients should be informed preoperatively of this possible decrease in CVA.
Collapse
Affiliation(s)
- K Nakamura
- Department of Ophthalmology, Tokyo Dental College, Chiba, Japan.
| | | | | | | | | |
Collapse
|