Transconjunctival corneoscleral tunnel "blue line" cataract incision.

PURPOSE: To report the technique and astigmatic results of the blue line cataract incision. SETTING: The Buzzard Eye Institute, Las Vegas, Nevada, USA. METHODS: This prospective study included 411 eyes of 271 patients who had cataract extraction by phacoemulsification with a self-sealing 3.0 mm blue line cataract incision. The blue line incision is performed with a diamond knife transconjunctively, 2.0 mm behind the surgical limbus. RESULTS: Mean patient age was 68 years (range 40 to 94 years) and mean preoperative astigmatism, 0.96 diopter (D) +/- 0.78 (SD). Uncorrected visual acuity at 1 day was 20/40 or better in 47% of patients. Mean spherical equivalent was -0.57 +/- 0.78 D at 6 months. Mean postoperative astigmatism measured with a subtraction method was 1.00 +/- 0.84 D at 6 months. Vector analysis showed an induced astigmatism of -0.47 +/- 1.00 D at 1 month, -0.58 +/- 0.81 D at 3 months, and -0.57 +/- 0.99 D at 6 months. No complications such as wound leakage or hyphema occurred. CONCLUSION: The blue line incision combines the efficiency of the clear corneal with the safety of the scleral tunnel cataract incision and appears to be relatively astigmatically neutral.

Reoperations after myopic laser in situ keratomileusis.

PURPOSE: To evaluate the results after enhancement of myopic laser in situ keratomileusis (LASIK) using the VISX Star excimer laser. SETTING: The Buzard Eye Institute, Las Vegas, Nevada, USA. METHODS: In this prospective study, 52 eyes of 40 patients had LASIK enhancement. The existing flap was lifted and the excimer laser treatment reapplied for the residual refractive error. The VISX Star excimer laser was used for the primary LASIK and the enhancement procedure. Retreatments for undercorrection, regression, and overcorrection were performed after 6 weeks and up to 40 weeks after the primary LASIK. Follow-up was 96% at 1 month, 67% at 6 months, and 71% at 12 months. RESULTS: Mean pre-enhancement spherical equivalent was -0.77 diopters (D) +/- 0.94 (SD) and mean uncorrected visual acuity (UCVA), 20/60. One year after the enhancement, mean spherical equivalent was -0.13 +/- 0.33 D, and mean UCVA was 20/25. Refraction remained stable during the 1 year follow-up, with no treatment required. After the enhancement, all patients had a UCVA of 20/40 or better. At 1 year, 3% of patients had lost 1 line of best corrected visual acuity and 32% had gained 1 line. No epithelial ingrowth was noted. CONCLUSION: Retreatment for LASIK beginning 6 weeks after the initial procedure proved to be effective with minimal complications and good results. The technique to raise and reposition the flap appeared safe, and complications were few.

Treatment of mild to moderate keratoconus with laser in situ keratomileusis.

PURPOSE: To evaluate the effectiveness, stability, and complications of laser in situ keratomileusis (LASIK) to treat myopic astigmatism in patients with keratoconus. SETTING: Buzard Eye Institute, Las Vegas, Nevada, USA. METHODS: This study included 16 eyes of 9 patients who had keratometric and/or clinical evidence of keratoconus. Mean age was 45 years, and refraction was stable for at least 2 years. Two treatment approaches were evaluated. RESULTS: Mean preoperative spherical equivalent was -4.23 diopters (D) +/- 2.14 (SD) with a mean steep keratometry of 46.81 +/- 3.07 D. Mean preoperative keratometric cylinder was 3.08 +/- 2.22 D. Mean postoperative keratometric cylinder was 3.00 +/- 4.78 D and mean spherical equivalent, -0.44 +/- 0.86 D. Mean postoperative steep keratometry was 44.12 +/- 7.17 D. Two eyes lost 1 line of best corrected visual acuity (BCVA), 1 eye lost 3 lines, and 2 lost 4 lines. Penetrating keratoplasty (PKP) was scheduled in 3 eyes 1 to 2 years after the primary LASIK. CONCLUSION: The initial visual results appear promising; but longer term results revealed regression of the refractive outcome in some cases. Moreover, despite improvement in the postoperative spherical equivalent and uncorrected visual acuity in most cases, the risk of loss of BCVA and the necessity of performing PKP in 3 cases lead us not to consider LASIK as a primary solution for keratoconus.

Excimer laser assisted in situ keratomileusis for hyperopia.

PURPOSE: To evaluate hyperopic surgical correction with 6.0 mm optical zone hyperopic laser in situ keratomileusis (LASIK) after various refractive procedures. SETTING: Buzard Eye Institute, Las Vegas, Nevada, USA. METHODS: This study followed 14 eyes of 14 patients who had hyperopic LASIK with a VISX Star laser. Mean follow-up was 8 months. The patients represented a variety of preoperative situations, including primary radial keratotomy (RK) (5 eyes) primary automated lamellar keratectomy (ALK) (2 eyes), primary LASIK (3 eyes), congenital hyperopia (1 eye), and combinations of ALK, RK, and LASIK. In all patients, a toroidal or "doughnut-shaped" ablation was constructed with the use of a 3.5 mm diameter soft contact lens as a blocking agent centrally with a 6.0 mm outside beam diameter. RESULTS: Mean preoperative spherical equivalent was +1.33 diopters (D) +/- 0.5 (SD) (range +0.50 to +1.88 D). The mean spherical equivalent was -0.32 +/- 1.20 D (range -1.25 to +2.63 D) at 1 month postoperatively and -0.15 +/- 0.60 D (range -1.13 to +1.25 D) at the last follow-up. Uncorrected visual acuity of 20/40 was obtained by 13 eyes (93%). No eye lost 2 or more lines of best corrected visual acuity at last follow-up. Four eyes required a postoperative LASIK enhancement procedure to correct induced myopia. No significant complications were seen. CONCLUSION: Hyperopic LASIK with the technique used in this study appeared safe, predictable, and stable. It represents a simple way to add hyperopic correction to existing laser systems.

Assessment of corneal wound healing by interactive topography.

INTRODUCTION: Constitutive properties of the cornea and wounds within the cornea have been measured previously by destructive methods in which a strip of cornea was removed, placed on an instrument, and stretched until broken. To assess corneal wound healing and the interaction of medication, incision patterns and other clinical issues, we present a simple, noninvasive test of corneal wound healing utilizing a videokeratoscope and Honan balloon. METHODS: A pre-test corneal topography was performed. The Honan balloon was placed on the eye at a pressure of 30mm mercury for 5 minutes. After removal of the balloon, additional corneal topographies were performed for comparison to the baseline topography. Study eyes were divided into six groups: 15 eyes in the normal group not involved in the Honan balloon test, 15 eyes formed a control group without previous ocular surgery, 15 eyes were within 3 months of radial keratotomy (RK), 15 eyes were more than 9 months after RK, 12 eyes had previous automated in situ keratomileusis (ALK), and 12 eyes had previous penetrating keratoplasty (PK). RESULTS: Average videokeratometric flattening was reported for all groups at intervals of 1, 2, and 3 minutes after removal of the Honan balloon. The normal group flattened by 0.04 +/- 0.10 D (range, +0.10 to -0.12 D) at 1 minute; 0.02 +/- 0.08 D (range, +0.10 to -0.10 D) at 2 minutes; and 0.02 +/- 0.06 D (range, +0.10 to -0.09 D) at 3 minutes. The control group flattened by -0.10 +/- 0.10 D (range, +0.30 to -0.30 D) at 1 minute; 0.01 +/- 0.12 D (range, +0.15 to -0.25 D) at 2 minutes; and 0.07 +/- 0.11 D (range, +0.14 to -0.18 D) at 3 minutes. The 3-month RK group flattened 0.95 +/- 0.23 D (range, 1.35 to 0.67 D) at 1 minute; 0.53 +/- 0.16 D (range, 0.71 to 0.39 D) at 2 minutes; and 0.40 +/- 0.15 D (range, 0.56 to 0.30 D) at 3 minutes. The 9-month RK group flattened 0.10 +/- 0.13 D (range, 0.23 to 0.02 D) at 1 minute; 0.10 +/- 0.12 D (range, 0.18 to -0.01 D) at 2 minutes; and 0.01 +/- 0.14 D (range 0.05 to 0.10 D) at 3 minutes. The ALK group flattened 0.65 +/- 0.42 D (range 0.98 to 0.38 D) at 1 minute; 0.27 +/- 0.19 D (range 0.39 to 0.10 D) at 2 minutes; and 0.21 +/- 0.17 D (range, 0.29 to 0.09 D) at 3 minutes. The PK group flattened 1.30 +/- 0.60 D (range, 1.75 to 0.90 D) at 1 minute; 1.18 +/- 0.43 D (range, 1.51 to 0.98 D) at 2 minutes; and 0.41 +/- 0.57 D (range, 0.88 to 0.30 D) at 3 minutes. CONCLUSIONS: We have established normal corneal wound healing curves from preliminary data utilizing Buzard interactive topography on normal control eyes and after radial keratotomy, automated lamellar keratoplasty, and penetrating keratoplasty. Deviation from these normal curves indicates either excessive or inadequate wound healing.

Corneal transplant for keratoconus: results in early and late disease.

PURPOSE: To evaluate the results and complications rates associated with corneal transplantation for keratoconus and assess the prospects of using penetrating keratoplasty at a much earlier stage. SETTING: Buzard Eye Institute, Las Vegas, Nevada, USA. METHODS: In this prospective clinical study, 104 eyes of 76 patients had corneal transplantation for keratoconus identified by corneal topography, keratometry, pachymetry, and/or retinoscopy. Sutures were removed at a mean of 15 months; mean follow-up was 42 months. All surgeries were performed by one surgeon using a torque-antitorque suture method. Eyes were grouped according to severity of the disease: early (n = 24); moderate (n = 47); high (n = 33). Preoperative keratometry was 40.00 to 49.00, 50.00 to 59.00, and 60.00 to 90.00 diopters (D), respectively. The criteria for corneal transplant were a best spectacle-corrected visual acuity of 20/40 or worse and keratoconus clearly identified by one of the above methods. Secondary procedures included repair of wound dehiscence (33 eyes, 31%), relaxing incisions (33 eyes, 31%), wedge resections (5 eyes, 5%), and automated lamellar keratoplasty (4 eyes, 4%). RESULTS: Mean postoperative uncorrected visual acuity at last follow-up was 0.43 +/- 0.3 (20/50), with 46 eyes (44%) achieving 20/40 or better. Mean best corrected visual acuity (BCVA) at last follow-up was 0.83 +/- 0.2 (20/25). Sixty eyes (58%) achieved 20/40 or better BCVA at 1 month and 92 eyes (88%), at 3 months. At last follow-up, mean average keratometric astigmatism was 3.10 +/- 1.70 D, mean keratometry was 43.30 +/- 2.20 D, and mean spherical equivalent was -1.70 +/- 3.00 D. Complications included 21 graft rejections (20%); 19 were successfully treated with topical and oral steroids. No expulsive hemorrhage or endophthalmitis occurred. CONCLUSIONS: The risk-benefit for corneal transplantation has been significantly altered by improved surgical and postoperative techniques. The improved results, low complication rate, and postoperative enhancement management indicate that corneal transplantation is a viable option early in the clinical course of keratoconus.

Radial and astigmatic keratotomy experience by residents and fellows at a teaching institution.

PURPOSE: To retrospectively study 30 cases of radial and astigmatic keratotomy performed by third-year ophthalmology residents and cornea fellows. SETTING: Tulane University Medical Center, New Orleans, Louisiana. METHODS: Patients were selected based on correction for stable myopia without or with astigmatism. Four or eight radial incisions were made using the Russian (uphill) method. The astigmatic cuts were straight transverse. RESULTS: Uncorrected visual acuity postoperatively was 20/40 or better in 28 eyes (93%). Two patients(visual acuity 20/50 and 20/70) were scheduled for secondary procedures but were lost to follow-up. Complications included three microperforations without sequelae. CONCLUSION: Radial and astigmatic keratotomy to correct myopia or myopia with astigmatism can be safe and effective in the hands of a beginning surgeon.

Treatment of irregular astigmatism with a broad beam excimer laser.

BACKGROUND: Four basic types of irregular astigmatism are described: central elevation, central flat area, eccentric elevation, and eccentric flat area. METHODS: The importance of the Munnerlyn formula is shown for the treatment of irregular astigmatism. A new diagnostic entity is described, the steep/flat ratio, modeled on the inferior/superior ratio described previously in keratoconus. Calculation of the steep/flat ratio is described using the cross sectional view of videokeratography, leading to specific treatments for the four types of irregular astigmatism. Surgical technique using the VISX Star excimer laser for repeated laser in situ keratomileusis (LASIK) is described. RESULTS: Case studies are given for each of the forms of irregular astigmatism showing improved topographic appearance and indicating treatment parameters. In each case, improvement of both uncorrected and spectacle-corrected visual acuity is demonstrated. CONCLUSIONS: Irregular astigmatism is an important complication of refractive surgery. Four basic forms of irregular astigmatism can be treated with a broad beam excimer laser.

Automated keratomileusis in situ: clinical study of 142 eyes.

PURPOSE: To compare a modified automated lamellar keratoplasty (ALK) technique that uses two blades with the original technique, which uses one blade. SETTING: Buzard Eye Institute, Las Vegas, Nevada. METHODS: This study comprised 142 eyes of 85 patients who had ALK: 107 using the original one-blade technique (Group 1) and 35 eyes using the modified two-blade technique (Group 2). Mean follow-up was 11 months in Group 1 and 3 months in Group 2. RESULTS: Mean preoperative spherical equivalent was -8.93 diopters (D) +/- 2.80 (SD) in Group 1 and -8.33 +/- 2.80 D in Group 2. No patient had worse than 20/80 best corrected visual acuity preoperatively. Mean spherical equivalent at 1 month was -2.06 +/- 2.00 D in Group 1 and -0.79 +/- 1.20 D in Group 2 (P < .05). Mean postoperative spherical equivalent at last follow-up was -0.43 +/- 0.90 and -0.65 +/- 1.10 D, respectively. At last follow-up, 104 eyes (97%) in Group 1 and 34 (97%) in Group 2 had a spherical equivalent between +1.00 and -3.00 D, and 90 eyes (84%) in Group 1 and 27 (77%) in Group 2 had 20/40 uncorrected visual acuity. Seven eyes (7%) in Group 1 and 1 (3%) in Group 2 lost two or more lines of best corrected visual acuity at last follow-up. Three months after ALK (for equal comparison), 25 eyes (23%) in Group 1 and 3 (8%) in Group 2 required radial keratotomy; 20 (19%) and 2 (6%), respectively, needed ALK revision; and 45 eyes (42%) and 17 (47%) needed astigmatic keratotomy. CONCLUSIONS: The results suggest that ALK is capable of impressive myopic corrections across a broad range of refractive error. The procedure is not accurate enough with a single microkeratome pass and requires enhancement procedures including recuts of the bed with the microkeratome and astigmatic and radial keratotomies. Using two blades to achieve an even cut gives better spherical equivalent and best corrected visual acuity results and lower enhancement rates.

Clinical results of arcuate incisions to correct astigmatism.

PURPOSE: To evaluate the effectiveness of arcuate incisions for correcting congenital, post-cataract, post-radial keratotomy, and post-trapezoidal keratotomy astigmatism. SETTING: Buzard Eye Institute, Las Vegas, Nevada. METHODS: In this retrospective study, 46 eyes of 29 patients had arcuate incisions to correct astigmatism. The average age of patients was 52 years. RESULTS: Mean preoperative astigmatism was 3.51 +/- 1.57 D (keratometric) and 3.41 +/- 1.44 D (manifest). Mean preoperative uncorrected visual acuity was 20/80, ranging from 20/30 to 20/400. Thirty eyes had a pair of 45-degree arcuate incisions, 10 eyes had a pair of 60-degree arcuate incisions, and 6 eyes had a pair of 90-degree arcuate incisions. Mean follow-up was 6 months. Mean postoperative astigmatism was 1.46 +/- 1.07 D (keratometric) and 1.05 +/- 0.94 D (manifest), with a reduction of astigmatism in all operated eyes. Mean postoperative uncorrected visual acuity was 20/32, ranging from 20/20 to 20/60. The analysis of the vector astigmatic change showed that only two patients were overcorrected after the procedure. CONCLUSION: The predictability and safety of arcuate incisions are reflected in these results.

Transient central corneal steepening after radial keratotomy.

Three case studies are presented illustrating topographic transient central steep island following radial keratotomy. Three stages are apparent: first, a central corneal steepening; next, an overcorrection with exaggerated central flattening; and, finally, the final refractive correction. The steepening is probably caused by temporary midperipheral swelling of the cornea.

New technique for studying incision depth in experimental radial keratotomy.

Older techniques of analyzing incision depth in incisional keratotomy consist of serial transverse sections taken at various points along the incision. Information as to shape and depth of the incision are reconstructed from these sections. We describe a new method for studying the incision depth and profile along the entire incision length.

Pilocarpine in the management of overcorrection after radial keratotomy.

BACKGROUND: Induced hyperopia is a potential complication of radial keratotomy with few effective treatments. We report the results of a retrospective study to evaluate the effectiveness of pilocarpine in the treatment of eyes overcorrected by radial keratotomy. METHODS: Sixteen eyes of 14 patients, from a consecutive pool of 200 eyes who underwent radial keratotomy, had hyperopia. The patients were subsequently treated with topical pilocarpine. The patients were treated from 3 to 14 weeks (mean, 8.2 weeks). RESULTS: The mean time of diagnosis of hyperopia was 3 weeks after the surgery (range, 1 to 12 weeks). The mean spherical equivalent of the manifest (fogging) refraction was +1.92 diopters (D) (range, +0.75 D to +5.00 D) and the keratometric power ranged from 31.25 D to 41.00 D (mean, 36.05 D). Mean uncorrected visual acuity before the treatment with pilocarpine was 20/50. After the treatment with pilocarpine, the mean spherical equivalent refraction was -0.31 D (range, -1.75 D to +0.50 D). The mean keratometric power was 38.32 D (range, 34.87 D to 43.12 D), with a mean uncorrected visual acuity at 20/25. The patients were followed for 8 to 49 weeks after treatment without pilocarpine (mean, 21 weeks). The mean spherical equivalent refraction and keratometric readings after that period were -0.71 D (range, -2.25 D to +0.25 D) and 38.33 D (range, 36.12 D to 43.12 D), respectively. All eyes in this study had more than 1.00 D of reduction of hyperopia at the conclusion of the study. CONCLUSION: Pilocarpine effectively reduced overcorrections after radial keratotomy. After termination of treatment, the steepening of corneal curvature was maintained.

Videokeratographic evaluation of peripheral redeepening in the cadaver eye.

Radial incisions must be deep enough to correct myopia. As currently performed, most surgeons set their diamond blades at a constant depth and do not alter the blade length throughout the procedure. The cornea is not uniformly thick; the central cornea is the thinnest and it thickens toward the periphery. Therefore, an incision of constant depth would be deeper centrally and thinner peripherally. Peripheral redeepening of the cornea would in theory make the incision depth deeper throughout and should increase the effect of radial incisions. We reviewed the literature on this technique and performed radial incisional studies on the human cadaver eye using videokeratography to measure incision depth indirectly. Based on our studies, we believe that peripheral redeepening has no effect on central cornea flattening.

Induction of astigmatism by straight transverse corneal incisions, 45 degrees long, at different clear zones in human cadaver eyes.

BACKGROUND: Two of the major factors affecting the amount of astigmatism correction are the length of the transverse incision and its distance from the center of the cornea. Many nomograms used in clinical practice have been created by varying the length or clear zone diameter of the incisions. A simplification of this situation has been suggested by Thornton, who has theorized that straight transverse incisions, subtending 45 degrees of arc, have equal astigmatic corrective effect at different clear zones. Our study tested Thornton's theory in human donor eyes. METHODS: Ten eyes were tested at four clear zones: 5.0, 6.0, 7.0, and 8.0 mm. Paired straight transverse incisions, subtending an arc of 45 degrees (2.1 to 3.3 mm long), were centered on the 90-degree meridian. Preoperative keratometric readings at the 180- and 90-degree meridians were compared to the postoperative readings; the difference was the total astigmatism induced. We also calculated the coupling ratio. RESULTS: Student's t-tests comparing clear zones 6.0 and 7.0 mm revealed a statistical difference (p = .0085) in total astigmatic induction, greater for the 6.0-millimeter zone. The coupling ratio decreased as the clear zone diameter increased, presumably as a result of diminished flattening effect along the incised meridian. One-way analysis of variance indicated that the groups were different (p = .0001), and that the theory noted above was incorrect. CONCLUSIONS: The effect of transverse incisions subtending the same angular length, drops off dramatically with clear zones larger than 6.0 mm, contrary to the theory of Thornton. This effect may be due to reduction in coupling as the clear zone diameter increases, suggesting that the greatest efficacy is achieved for transverse incisions placed between 5.0- and 6.0-millimeter zones.

Control of astigmatism aided by intraoperative keratometry.

An evaluation of the final "sutures out" postoperative astigmatism in two groups of keratoconus patients undergoing penetrating keratoplasty is presented. Group I consists of a retrospective evaluation of keratoconus patients who underwent penetrating keratoplasty without using the Troutman Keratometer prior to suturing the button into position. Group II patients had their donor button rotated in the recipient bed until approximate sphericity was indicated by a circular reflex from the Troutman Keratometer before suturing into position. The mean final astigmatism with all sutures removed from Group I was 4.64, SD 1.89, and for Group II 2.27, SD 1.27. Selective positioning of the donor button using the Troutman Keratometer leads to a significant reduction in the final sutures out astigmatism in patients undergoing penetrating keratoplasty for keratoconus.

Circumferential block resection to reduce myopia.

BACKGROUND: The surgical treatment of excessive myopia following penetrating keratoplasty has been largely ignored. Oversized corneal grafts can induce myopia and the Troutman wedge (block) resection has been used to correct astigmatism by removing tissue in a single corneal semimeridian. This study explores the use of block resections in opposing semimeridians to reduce myopia caused by a steep cornea. METHODS: Six eyes received three different operations. One eye received 60-degree block resections in semimeridians located 90 degrees (procedure 1), two eyes received 0.5-millimeter semicircumferential (180 degrees) block resections (procedure 2), and three eyes underwent 0.5-millimeter 360-degree circumferential block resections (procedure 3). All patients were followed for at least 1 year. RESULTS: Procedure 1 (two 60-degree block resections) developed approximately 2.75 D of myopic correction at 1 year. The average reduction of spherical equivalent was 4.50 D for procedure 2 (one 180-degree block resection) and 10.50 D for procedure 3 (one 360-degree block resection) at 1 year. Although all eyes regained best spectacle-corrected visual acuity, the postoperative course was prolonged by irregular astigmatism. CONCLUSIONS: Circumferential and semicircumferential block resections can reduce myopia after penetrating keratoplasty and in naturally-occurring myopia, but the postoperative course can be prolonged, especially because of irregular astigmatism. Early removal of sutures results in regression of myopic correction.

Quantitative measurement of wound spreading in radial keratotomy.

BACKGROUND: Many studies of radial keratotomy have been performed, however quantitative laboratory evaluation of the biomechanics of this procedure is still incomplete. Furthermore, most measurements of strain in the past have utilized strip testing, thus destroying the normal physiological structure and water balance of the cornea. METHODS: We report on a membrane inflation method of wound spreading in intact human corneas using the Baribeau Micronscope. RESULTS: We measured a secant elastic modulus of 7.58 x 10(6) N/m2 between 25 and 100 mm Hg. The spreading of radial keratotomy incisions as a function of intraocular pressure showed a maximum spreading of approximately 50 mu at 25 mm Hg at a radius of 3.50 mm from the optical center. A slight increase in spreading was observed in proceeding from a single to four radial incisions. CONCLUSIONS: Quantitative measurement of wound spreading is an important parameter of radial keratotomy and can provide important information regarding opposing theories of the biomechanics of this operation.

Compression sutures and penetrating corneal trauma.

A simple technique involving additional compression sutures and the use of a subjective operating keratometer is described for use in managing excessive astigmatism following suturing for penetrating corneal trauma. By minimizing "sutures in" astigmatism following wound closure, this technique can hasten visual rehabilitation.