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A series of 100 patients had cataract extraction with intraocular lens implantation by the endocapsular method of Galand. The astigmatism was assessed at two, six, and 18 weeks postoperatively. The incision and closure and the methods of correcting postoperative astigmatism are discussed.
Astigmatic changes in three series of cataract surgical procedures were compared. Two series comprised eyes having phacoemulsification and implantation of a foldable silicone lens through a 3.0 mm to 4.0 mm incision or a 5.8 mm diameter polymethylmethacrylate (PMMA) lens through a 6.0 mm incision. The third series comprised eyes having a planned extracapsular cataract extraction (ECCE) procedure through a 10.0 mm incision and implantation of a PMMA posterior chamber lens. Surgically induced cylinder changes were compared by examining preoperative and postoperative dioptric cylinder power changes without regard to axis changes and by using vector analysis to compute induced cylinder for cases with axis changes. Both phacoemulsification series had similar mean induced cylinder levels, which were significantly less than mean induced cylinder in the ECCE group at both three and six months after surgery. Over 70% of the eyes in the two small incision phacoemulsification groups achieved an uncorrected visual acuity of 20/40 or better at three months, whereas only 28% of the ECCE group achieved that acuity. We concluded that the phacoemulsification procedure induced significantly less astigmatism and provided faster visual rehabilitation than the ECCE procedure. Furthermore, the use of small diameter PMMA IOLs inserted through small incisions minimized surgically induced cylinder in a way comparable to the use of foldable silicone implants, while maintaining good visual results with fewer postoperative complications.
OBJECTIVES: To verify corneal topography and astigmatism after cataract surgery with 8 mm scleral tunnel incisions closed with a continuous 10-0 nylon suture. SETTING: Institute of Ophthalmology, University of Verona, Italy. METHOD: Twenty eyes were studied for 12 months after cataract extraction with 8 mm, sutured, scleral tunnel incisions. Corneal topography (EyeSys 2.1) was evaluated for the first 5 months. Astigmatism (absolute and induced) was measured by Javal ophthalmometry preoperatively and 1, 7, 30, 60, 90, 150, and 360 days after surgery. RESULTS: In the week following surgery, corneal shape was minimally affected and uncorrected visual acuity was not compromised. Mean with-the-rule induced cylinder was less than 1.00 diopter (D). After 5 and after 12 months, the mean induced cylinder was still less than 1.50 D but with an against-the-rule shift in almost all eyes. CONCLUSIONS: Sutured 8 mm tunnel incisions showed good results in terms of absolute cylinders but late against-the-rule shift could not be avoided.
PURPOSE: To assess the results of surface sequential toric photorefractive keratectomy (PRK) with the Summit Apex Plus excimer laser using an erodible mask. METHODS: A prospective study was performed on consecutive eyes having surface sequential toric PRK over a 4 month treatment period. Attempted astigmatism correction varied from 70 to 100%, depending on the power and axis of the cylinder. The myopic correction was adjusted so the combined treatment aim was emmetropia. Refraction, manual keratometry, corneal haze, and visual acuity data from preoperative and follow-up visits over 12 months were divided into various groups based on the preoperative refraction and analyzed. RESULTS: Fifty-nine eyes from 48 patients had sequential toric PRK. Preoperatively, the mean spherical equivalent at glasses plane (SEGP) was -4.88 diopters (D) +/- 3.20 (SD) and the mean refractive cylinder, 2.02 +/- 1.04 D. The mean attempted cylinder correction was 1.87 D. At 12 months the mean SEGP was -0.02 +/- 0.67 D, which was not statistically significant from plano. The mean refractive cylinder was 0.84 +/- 0.84 D, which was statistically significantly different from zero cylinder power. There was a statistically significant correlation between the preoperative and the 12 month postoperative refractive cylinder powers. At 12 months, 34 of 43 eyes (79.1%) had an uncorrected visual acuity of 6/12 or better. While 2 eyes in one patient (4.7%) lost two lines of best corrected visual acuity, with a final acuity of 6/12 in each, no patient lost more than two lines. CONCLUSION: The manifest refraction cylinder power is not fully corrected with the current treatment algorithms; however, surface sequential toric PRK using an erodible mask is capable of treating compound myopic astigmatism with moderate success.
PURPOSE: To compare the visual outcome, change in surgically induced astigmatism, and corneal thickness after sutureless cataract surgery through either a scleral tunnel or clear corneal incision. SETTING: Department of Ophthalmology, Kangnam St. Mary's Hospital, Catholic University Medical College, Seoul, Korea. METHODS: This retrospective study evaluated 79 eyes of 64 patients who had cataract surgery using a 6.0 mm scleral tunnel incision (Group 1, n = 20 eyes), 3.1 mm clear corneal incision at the 10 o'clock position (Group 2, n = 35 eyes), or 3.1 mm clear corneal incision at the 10 o'clock position (Group 3, n = 24 eyes). Changes in surgically induced astigmatism were analyzed using computer-assisted videokeratography (CVK) 1 day, 8 weeks, and 6 months postoperatively. RESULTS: Eleven eyes (55.0%) in Group 1, 15 (42.8%) in Group 2, and 11 (48.5%) in Group 3 had an uncorrected visual acuity of 20/40 or better 1 day postoperatively. The CVK measurements showed significantly more flattening at radial distances of 0.75, 1.50, and 2.50 mm along the 90 degree semimeridian in Group 2 than in Group 1 (P < .05) 1 day after surgery; in Group 3, flattening along the incisional semimeridian fell between the amounts in Groups 1 and 2. At 8 weeks, the amount of flattening decreased in all groups, and the differences between groups were not statistically significantly different (P > .05). In the CVK pattern, corneal flattening along the incisional meridian was narrower and longer in Groups 2 and 3 than in Group 1. CONCLUSION: Localized flattening along the incisional meridian was prominent temporally after clear corneal incision surgery. However, there was no difference in early visual rehabilitation between the clear corneal and scleral tunnel incision groups.
PURPOSE: To compare short-term clinical, postoperative astigmatism, and uncorrected visual acuity results 2 months after no-stitch phacoemulsification using a temporal clear corneal approach and poly(methyl methacrylate) (PMMA) intraocular lens (IOL) implantation through a 5.2 mm incision with those after no-stitch superior corneoscleral phacoemulsification. SETTING: University Eye Clinic of Palermo, Italy. METHODS: This prospective clinical trial comprised 80 patients with senile cataract who were randomly assigned to have phacoemulsification using a temporal approach or a superior approach. Surgically induced astigmatism (SIA) was calculated using Naeser's polar value method for determining with-the-rule (WTR) or against-the-rule (ATR) change. RESULTS: There was a highly significant between-group difference in SIA at each examination (P < .001; t-test) because of positive (WTR) SIA in the temporal approach group and negative (ATR) SIA in the superior approach group. No other significant differences between groups were found (P < .05, t-test). More patients in the temporal group had an uncorrected visual acuity of 20/25 or better 2 weeks postoperatively, although the difference between groups was not statistically significant (P = .562; chi-square). CONCLUSION: Phacoemulsification using a no-stitch, temporal, 5.2 mm clear corneal incision produced results comparable to those using a corneoscleral superior approach. A longer study of a larger series should be done to confirm the findings.
PURPOSE: To assess the long-term stability of cataract wounds of various lengths. SETTING: Private practice. METHODS: This retrospective study comprised 5 groups of consecutive cataract surgery cases and 1 control group with similar mean ages and wound lengths of 10.0, 6.0, 4.0, 2.0, and 0 (control) mm. Except for the 4.0 mm cases, follow-up was 5 years, with few patients lost during that time. Cases within each group had the same wound position, configuration, and suturing. Refractive data, controlled by keratometry, were collected and analyzed preoperatively and 1 day, 1 and 6 weeks, 3 and 6 months, and 1, 2, 3, 4, and 5 years postoperatively. No sutures were cut. RESULTS: With long-term follow-up, there was a progressive against-the-rule shift in astigmatism. Smaller wounds showed less immediate induced astigmatism. However, except for the unsutured 2.0 mm iridectomy wounds and the control group, all shifted similarly. Data were not available for the 4.0 mm wounds beyond 1 year. CONCLUSION: Wounds were not necessarily "stable" at 6 months. Larger wounds continued to shift years after surgery. Smaller wounds have significant postoperative advantages, but absolute long-term refractive stability may not be one.
Soft contact lens correction for astigmatism has made significant advances over the last 20 years. Soft toric tinted lenses, disposables lenses, and bifocal lenses are now available at lower costs with greater reproducibility, enhanced parameters, and better comfort. Because of these innovations and significant design changes, a greater percentage of astigmatic patients are being treated with soft toric lenses than before.
INTRODUCTION: Visual acuity screening (VAS) is less reliable in preschoolers than in school-aged children as a means of detecting significant refractive error. We wished to compare the effectiveness of VAS with the effectiveness of an objective method, noncycloplegic autorefraction screening (NCARS), in detecting the presence of significant astigmatism warranting spectacle correction. METHODS: We examined 245 Native American Head Start registrants aged 3 to 5 years. We attempted to obtain uncorrected visual acuity using Lea Symbols logMAR Chart (Precision Vision Inc, Villa Park, Ill), noncycloplegic autorefraction using the Nikon Retinomax K-plus (Nikon Corp, Melville, NY), and cycloplegic refraction (CR) on each eye. The VAS failure criterion was either a 2-line acuity difference between eyes or acuity worse than 20/40 in either eye. The NCARS and CR failure criterion was the spectacle correction threshold exceeding the 50th percentile on the basis of a survey of AAPOS members. RESULTS: We completed VAS in 96% of children and NCARS and CR in 100% of children. There was high prevalence (31%) of significant astigmatic refractive error in this sample. Ten subjects who did not permit bilateral visual acuity measurements were scored as having a positive test result. The sensitivity and specificity of VAS were 90% and 44%, respectively. NCARS had sensitivity and specificity of 91% and 86%, respectively. NCARS becomes cost-effective after 1044 children are screened, assuming that the cost of the autorefractor is 300 times the cost of the referral examination. CONCLUSION: VAS offers high sensitivity but suffers from poor specificity. NCARS greatly reduces the number of unnecessary referrals. In this population, NCARS becomes cost-effective after approximately 1000 children are screened.
A prospective study compared post-operative astigmatism and visual acuity (corrected and uncorrected) following phacoemulsification and extracapsular surgery. Fifty eyes had implantation of a 7 mm diameter optic intraocular lens (IOL) following conventional extracapsular cataract extraction (ECCE) with a 10 mm corneal incision. Forty-seven eyes were implanted with a 5 x 6 mm optic IOL through a 5 mm scleral incision after phacoemulsification. Uncorrected visual acuity of 6/9 or better was achieved in 25% of eyes on the first day following phacoemulsification, 36% at 1 week and 57% at 12 weeks. These results (and also the best corrected acuity) were significantly better than those following ECCE. Less astigmatism was induced by phacoemulsification than extracapsular surgery, measured at all post-operative time intervals.
A prospective, randomised study was carried out in 135 patients to determine whether the time of removal of continuous sutures in the relief of post-operative astigmatism had any effect on subsequent changes in cylinder power or axis. After uncomplicated extracapsular cataract extraction with a corneal section and continuous 10/0 nylon suture, patients with more than 3 dioptres of cylinder were allocated to have their suture removed at 6, 9 or 12 weeks post-operatively. Visual and optical outcome were assessed 1 week after suture removal and at 6 months. Although the time of removal did not affect the change in cylindrical power, the subsequent refraction was more stable when the suture was removed at 12 weeks. However, initial against-the-rule astigmatism did not significantly change after suture removal and resulted in an unsatisfactory final prescription. Suture removal should therefore be performed at 12 weeks, glasses should not be prescribed early, and a poor outcome may be anticipated in those initially against-the-rule.
PURPOSE: To determine whether clear cornea temporal sutureless sections lead to astigmatic decay over a 2 year period. METHOD: The difference between (a) pre-operative keratometric cylinder and keratometric cylinder at final follow-up, and (b) spectacle cylinder at 1 month post-operation and final follow-up, was calculated for 43 eyes. RESULTS: The mean difference in keratometric cylinder between pre-operation and final follow-up was 0.12 D with the rule (WTR) or against the wound. The range was from 0.7 D WTR to 0.4 D against the rule (ATR). Eighty-two per cent of eyes did not change by more than 0.3 D. The mean change in spectacle prescription between 1 month post-operation and final follow-up was 0.05 D ATR, range 0.5 D WTR to 1.0 D ATR. At final follow-up 93% of eyes were seeing 20/40 or better unaided. CONCLUSION: A carefully constructed temporal wound can remain astigmatically neutral.
PURPOSE: To analyse the early surgically induced corneal astigmatism (SICA) with a 3.5 mm oblique clear corneal incision (CCI) for phacoemulsification and flexible silicone implant. METHODS: Sixty-four consecutive patients were included in this study. The keratometry readings were recorded on the day prior to surgery, the first day post-operatively and at 6 weeks. The SICA was evaluated according to four different methods: (i) simple subtraction, (ii) vector analysis, (iii) vector decomposition and (iv) Naeser polar values. RESULTS: At 6 weeks post-operatively the SICA was equally divided between with-the-rule (WTR) and against-the-rule (ATR) astigmatism, according to the vector analysis in combination with vector decomposition. Both the simple subtraction method and Naeser polar values were misleading. CONCLUSION: The oblique clear corneal section for phacoemulsification is a comfortable and safe incision with a predictable and acceptable degree of SICA that may be better tolerated than that induced by superior incision.
The stenopaeic slit is a trial case accessory used in subjective refraction, especially when high astigmatism is present. In spite of its simplicity, the effect of the slit when it is not oriented along one of the principal meridians of the examined eye is difficult to predict, even in terms of classical geometrical optics. In this paper, the optical principles of the slit are considered with full details in the theoretical framework of the dioptric power space. An analytical expression to obtain the residual refractive error when a stenopaeic slit is placed in front of an astigmatic eye at any orientation is deduced. In the light of these results, some aspects of the clinical procedure are discussed.
The course of postoperative astigmatism was studied in 2 groups of patients following phacoemulsification and IOL implantation. In the first group a soft posterior chamber lens (IOGEL, Alcon) was introduced through a 6.5 mm scleral pocket incision. In group 2 the IOGEL lens was implanted through a 3.5 mm incision using a new instrument. The patients in group 2 had lower postoperative astigmatism and achieved stable refraction significantly earlier than group 1 patients. Three weeks postoperatively changes in refraction were seen in only a few cases. The small-incision technique significantly accelerates the visual rehabilitation of cataract patients.
Excimer laser corneal T-excisions for the correction of astigmatism in eight eyes followed up for three months postoperatively revealed an effective change in refraction of up to 4.2 diopters. The effect depends on the depth of the excision. Although the clinical results agree with astigmatism theory predictions from a biomechanical model of the cornea, some features are not explained by the model. The temporal behavior of the changes in refraction subsequent to excimer laser excisions differ from those produced by blade incisions, indicating a different repair mechanism. The keratectomy technique employed did not result in any serious side effects.
The postoperative astigmatism of 987 eyes after cataract extraction was studied with reference to behavior in the course of time, axis, and amount. The late post-operative distribution (6 months) of astigmatism approximates the preoperative values. Using Euler's method, the influence of surgical technique and surgeon on the refractive power of the cornea was investigated. The standard deviation of refractive power is more than twice the influence of surgeon and different surgical technique (extracapsular cataract extraction versus phakoemulsification).
Corneal astigmatism after keratoplasty can be treated optically or surgically. If a step forms after surgery or after removal of the sutures, resuturing is necessary. In cases of extreme astigmatism which are optically not correctable, surgical methods such as keratotomy, keratocauterization or keratoresection have been suggested. The excision of a corneal wedge, introduced in 1975, is a useful method which has now become established. The technique and the results in 8 cases are presented.