Phacoemulsification surgery by a nationally-trained cataract surgeon of Nepal

INTRODUCTION

A one month phacoemulsification training course had been implemented by the Nepal Netra Jyoti Sangh (NNJS) in collaboration with Association for Ophthalmic Cooperation to Asia, Japan (AOCA).

OBJECTIVE

To evaluate the visual outcomes of phacoemulsification surgery by a nationally trained surgeon in Nepal.

MATERIALS AND METHODS

A retrospective study of patients that underwent phacoemulsification with foldable intraocular lens implantation during a period of 18 months was carried out. Cases that had a six-week follow-up period were included. Effective phaco time (EPT), intra-operative and postoperative complications were noted. Uncorrected visual acuity (UCVA) at day 1 and best corrected visual acuity (BCVA) at week 6 were noted. The data were analyzed using SPSS 11.5.

RESULTS

A total of172 patients that had completed a 6 week follow-up evaluation were included in the study. The mean age of patients was 57.12±10.19 years. The mean effective phaco time (EPT) was 9.74±7.41 seconds. Posterior capsule rupture (PCR) with vitreous loss occurred in 2 eyes (1.2%), Descemet's membrane detachment in 1 eye (0.6%), capsulorhexis extension in 1 eye (0.6%) and wound site thermal injury (WSTI) occurred in 3 eyes (1.7%). Postoperative complications were mild to moderate striate keratopathy (9/ 172), corneal edema (1/172), corneal epithelial defect (1/172) and uveitis (1/172). At 6 weeks post-operatively, 165 eyes (95.9%) had a BCVA better than 6/18 and 7 eyes (4.1%) had a BCVA of 6/18 to 6/60.

CONCLUSION

Patients undergoing phacoemulsification had a good visual outcome as a result of the procedure performed by cataract surgeon trained from AOCA/NNJS national phacoemulsification training program of Nepal.

Clinical application of full-arc, depth-dependent, astigmatic keratotomy

PURPOSE

To report a case series of the first clinical application of a new method of astigmatic keratotomy termed full-arc, depth-dependent astigmatic keratotomy (FDAK).

METHODS

The type of astigmatism was analyzed by corneal topography. If the astigmatism was regular, paired arcuate incisions of 90 degrees length were used. Incision depth varied between 40% and 75% of local corneal thickness for controlling the level of astigmatic correction.

RESULTS

All 13 cases had regular astigmatism, and paired arcuate incisions of 90 degrees length were used. Four cases with incisions at 40% depth, five cases at 50% depth, three cases at 60% depth, and one case at 75% depth induced vector astigmatic change of 0.93 +/- 0.33 D, 1.92 +/- 0.24 D, 3.17 +/- 0.26 D, and 4.44 D, respectively, 3 months after surgery. From 3 months to 1 year or 3 years, the postoperative astigmatism was stable, and no cases showed astigmatic regression of 0.50 D or more. Every topographic difference map indicated effective flattening and steepening occurring with a 1:1 coupling ratio. All postoperative color maps showed a marked improvement in corneal sphericity.

CONCLUSIONS

In FDAK using paired 90 degrees incisions at 40-75% depth, an almost linear relationship between the incision depth and degree of astigmatic change was observed. FDAK may be an effective and safe method of astigmatic keratotomy that accurately controls the level of astigmatic correction. More clinical applications are necessary for drawing final conclusions and making a nomogram.

Macular fold after limited macular translocation treated with scleral shortening release and intravitreal gas

PURPOSE

To describe a case developing a macular fold as a complication of limited macular translocation, which was successfully managed without repeat vitrectomy.

METHODS

Interventional case report. A 34-year-old woman who underwent limited macular translocation for subfoveal choroidal neovascularization secondary to myopic degeneration developed a postoperative macular fold. Her visual acuity deteriorated from 20/100 to 20/200 postoperatively.

RESULTS

She underwent scleral shortening release and intravitreal gas injection 4 days after the initial surgery and had a resolution of macular fold with adequate foveal displacement. Her visual acuity had improved to 20/40 3 months postoperatively.

CONCLUSION

Scleral shortening release and intravitreal gas injection may be considered for the management of severe macular fold caused by limited macular translocation.

Measures for preventing recurrence after pterygium surgery

PURPOSE

To introduce an improved technique of pterygium surgery and to compare postoperative results between this technique and previous techniques.

METHODS

In a retrospective survey, the records of 216 consecutive eyes with primary pterygium that underwent surgery by three different techniques were reviewed. The new technique (mini-flap technique) involves making a small excision of the pterygium body, removing the pterygium head by scraping with forceps, applying mitomycin C (MMC), and performing a small conjunctival transposition flap. The previous technique (large-flap technique II) involved making a large excision in the pterygium body, removing the pterygium head with a knife, applying MMC, and performing a large transposition flap. Large-flap technique I is the same as large-flap technique II except for the use of intraoperative MMC. The recurrence rate of each technique was estimated by the Kaplan-Meier life table analysis.

RESULTS

The recurrence rates estimated at 1 year after surgery were 15.5% in large-flap technique I, 4.2% in large-flap technique II, and 0% in the mini-flap technique. Large-flap technique II or the mini-flap technique had significantly lower recurrence rates compared with large-flap technique I ( p = 0.02 and p < 0.01, respectively). The mini-flap technique had a significantly lower incidence of conjunctival scarring or granuloma compared with large-flap technique I and large-flap technique II ( p = 0.05 and p = 0.03, respectively.)

CONCLUSIONS

The mini-flap technique was useful for preventing recurrence and was technically easier and induced fewer postoperative complications than large-flap techniques I and II.

Capsular bending ring to prevent posterior capsule opacification: 2 year follow-up

PURPOSE

To evaluate the preventive effect of a capsular bending ring on anterior and posterior capsule (PCO) opacification in a 2 year clinical study.

SETTING

Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.

METHODS

This study comprised 60 patients with senile cataract (35 women, 25 men) with a mean age of 69 years. An open poly(methyl methacrylate) capsular bending ring with a truncated edge profile designed to create a sharp bend in the equatorial capsule was implanted in 1 eye of patients with a hydroxyethyl methacrylate intraocular lens (IOL). The contralateral eye, which acted as a control, received an IOL but no ring. Patients were examined 6 months (n = 52), 1 year (n = 48), and 2 years (n = 42) postoperatively. Anterior capsule opacification was determined by slitlamp evaluation. Anterior capsule shrinkage (area within the capsulorhexis) and PCO were evaluated and scored using a computer software package for image analysis. Posterior capsule opacification was also measured by the rate of neodymium:YAG (Nd:YAG) capsulotomies.

RESULTS

Anterior capsule opacification and shrinkage were significantly less in eyes with the ring. The mean PCO score was 0.235 +/- 0.215 (SD), 0.287 +/- 0.200, and 0.398 +/- 0.248 with the ring and 0.530 +/- 0.190, 0.670 +/- 0.225, and 1.111 +/- 0.298 without the ring at 6 months, 1 year, and 2 years, respectively (P <.01 at each follow-up). An Nd:YAG laser capsulotomy was performed in 4 eyes with and 17 eyes without the ring after 2 years (P <.01).

CONCLUSIONS

The capsular bending ring significantly reduced anterior capsule fibrosis and shrinkage as well as PCO. The ring may be useful in patients who are at high risk of developing eye complications from capsule opacification that require Nd:YAG laser capsulotomy, in those expected to have vitreoretinal surgery and photocoagulation, and in cases of pediatric cataract.

Inhibition of lens epithelial cells by Fas-specific antibody activating Fas-Fas ligand system

PURPOSE

To detect cell specific apoptosis factors, Fas and Fas ligand, and the common intracellular apoptosis modulators, interleukin-1 beta converting enzyme (ICE)-like protease (caspase 1), Bcl-2, Bcl-xL and Bax in lens epithelial cells (LEC) of human cataracts. To study the effects of Fas-stimulating monoclonal antibody on inhibition of LEC proliferation.

METHODS

Reverse-transcriptase-polymerase chain reaction (RT-PCR) was used to detect Fas, Fas ligand, caspase 1, Bcl-2, Bcl-xL and Bax, after cDNA was synthesized from the total RNA isolated from human cataractous LEC obtained by capsulotomy during cataract surgery. Fas-stimulating monoclonal antibody was added at the concentrations of 10, 30, 100, 300 and 1000 ng/ml to the incubation medium of human cataractous LEC; and the specimens were incubated for 24 h at 37 degrees C with 5% CO(2) circulation and 100% humidity. The specimens were then stained with Hoechst 33342, and the number of apoptotic cells was counted.

RESULTS

Fas, caspase 1, Bcl-2, Bcl-xL and Bax mRNA were detected by RT-PCR. Fas ligand mRNA was not detected by RT-PCR. At each concentration, Fas-stimulating monoclonal antibody significantly inhibited LEC proliferation.

CONCLUSIONS

Human cataractous LEC expressed mRNA of Fas and various modulators of apoptosis pathways. Fas-stimulating monoclonal antibody may have the potential to prevent posterior capsule opacification after cataract surgery by inhibiting LEC proliferation.

Management of posterior capsule rupture during phacoemulsification using the dry technique

To manage posterior capsule rupture during phacoemulsification, we use a dry technique in which all procedures are performed without an irrigation/aspiration system. The dry technique is characterized by (1) continuous viscoelastic injection instead of fluid irrigation to maintain anterior chamber depth with the posterior capsule and vitreous located posteriorly and (2) static removal of most residual lens material by viscoexpression and/or manual small incision extracapsular cataract extraction without aspiration and dynamic water flow. In 16 cases of posterior capsule rupture managed using the dry technique, the residual nucleus and cortex were readily removed with minimum extension of the ruptured area and new vitreous loss. Although large amounts of viscoelastic material (mean 5.8 mL) were required, rapid and stable visual recovery was comparable to that in patients having uneventful surgery. The dry system is a safe and reliable technique for managing posterior capsule rupture during phacoemulsification.

Macular star associated with posterior hyaloid detachment

PURPOSE

To report a patient with a Leber's idiopathic stellate neuroretinitis-like lesion that was caused by vitreous traction accompanying a posterior hyaloid detachment.

METHODS

We present a 49-year-old woman who showed segmental optic disc edema, peripapillary retinal detachment, and a macular star.

RESULTS

An incomplete posterior hyaloid detachment was present, and the posterior hyaloid membrane was attached to the nasal margin of the optic disc. Fluorescein angiography revealed a bent retinal artery on the upper margin of the optic disc, and leakage of fluorescein was observed from this area.

CONCLUSION

Vascular damage to the optic disc due to vitreous traction should also be considered as a mechanism for the ophthalmoscopic appearance of the fundus when lesions suggestive of Leber's idiopathic stellate neuroretinitis are present in an adult.

Differences in incision shape based on the keratome bevel

PURPOSE

To evaluate differences in incision shape due to the bevel of the keratome.

SETTING

Kushimoto Rehabilitation Center, Kushimoto, Japan.

METHODS

Three types of keratomes (bibevel, bevel up, and bevel down) were inserted into soft polyvinyl chloride sheets and polyurethane sheets, and the incision shapes in the blade entrance and exit planes were evaluated. The experiments were repeated using soft polyvinyl chloride domes and silicone domes.

RESULTS

In the experiments using artificial sheets, the incisions in the blade entrance and exit planes using the bibevel keratome had a linear shape, those using the bevel-up keratome had an inverse-V shape, and those using the bevel-down keratome had a V shape. In the experiments using artificial domes, the incision shapes were the same as those in the artificial sheets.

CONCLUSIONS

The incision shape differed according to the direction of the keratome bevel. These experiments and results may provide useful data when new knives are developed or when incision shapes following intended specifications are stably made.

Experimental study using pig eyes for realizing ideal astigmatic keratotomy

PURPOSE

The effects of varying the incision length and depth were analyzed using pig eyes to acquire information for realizing an ideal method of astigmatic keratotomy (AK).

METHODS

Single and paired arcuate incisions were made on pig corneas using a diamond knife. Incisions with varying lengths of 40 degrees, 60 degrees, and 90 degrees were made with the incision depth fixed at 90% of corneal thickness. Next, paired incisions with varying incision depth from 20% to 95% of corneal thickness were made with the incision length fixed at 90 degrees. The changes in corneal shape were analyzed using corneal topography and the degrees of astigmatic change were measured using a surgical keratometer.

RESULTS

For short single and paired incisions (40 degrees or 60 degrees in length), narrow areas of flattenings occurred, and steepenings were observed on both sides adjacent to the flattened areas. For long paired incisions of 90 degrees length, wide areas of flattenings and steepenings were observed with an approximately 1:1 coupling ratio, and a positive linear relationship between the incision depth and degree of astigmatic change was observed in the range of incision depth between 40% and 80% of corneal thickness.

CONCLUSION

This experimental study suggests that for achieving ideal corneal sphericity after AK, long incisions covering the entire steep areas (paired 90 degrees incisions for regular astigmatism) should be used and the degree of astigmatic correction may be controlled by varying the incision depth.

Effect of round-edged acrylic intraocular lenses on preventing posterior capsule opacification

PURPOSE

To clarify the extent to which the adhesiveness of an acrylic material influences the formation of posterior capsule opacification (PCO).

SETTING

Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan.

METHODS

Two types of AcrySof(R) intraocular lenses (IOLs) were prepared: round edged and tumbled. The AcrySof with round edges was implanted in 1 eye in a group of 4 rabbits and the tumbled IOL, in 1 eye in a group of 5 rabbits. In both groups, the contralateral eye received a conventional AcrySof with sharp optic edges. A histopathological examination was performed 3 weeks after surgery.

RESULTS

With the round-edged AcrySof IOL, no capsular bend formed at the optic edge and abundant lens epithelial cells (LECs) migrated posteriorly. With the sharp-edged AcrySof lens, a sharp capsular bend formed and LEC migration was significantly inhibited. In eyes with a tumbled IOL, a capsular bend was created, but it was less marked than that created by the sharp-edged lens and there was slightly more LEC migration posteriorly.

CONCLUSIONS

The AcrySof IOL lost its preventive effect on PCO when the optic was rounded. The effect of the AcrySof lens in preventing PCO is mainly a result of its rectangular, sharp-edged optic design. The acrylic material may play a complementary role by helping create a sharp capsular bend. Capsular bend formation is the key to the PCO preventive effect of an IOL.

Enhanced disruption of the blood-aqueous barrier and the incidence of angiographic cystoid macular edema by topical timolol and its preservative in early postoperative pseudophakia

OBJECTIVE

To investigate the effects of timolol maleate with preservative and its preserved (PV) and nonpreserved vehicles (NPV) (benzalkonium chloride) on the blood-aqueous barrier and angiographic cystoid macular edema (CME) in early postoperative pseudophakia.

PATIENTS AND METHODS

Patients with ocular hypertension, normal tension glaucoma, and primary open-angle glaucoma who underwent surgery for cataracts. The study included a double-masked trial for timolol, PV, and NPV and a single-masked trial on the effect of diclofenac sodium and fluorometholone acetate on all three. The patients were divided into 6 groups, each of which were simultaneously administered the following different combinations of compounds: timolol and diclofenac (group A), timolol and fluorometholone (group B), PV and diclofenac (group C), PV and fluorometholone (group D), NPV and diclofenac (group E), and NPV and fluorometholone (group F). The 6 groups were then compared using a laser flare cell meter to determine the degree of disruption of the blood-aqueous barrier and fluorescein angiography to investigate angiographic CME. The differences in mean daily fluctuations in intraocular pressure were compared on the preoperative baseline day and for 5 weeks postoperatively. Twice daily administration of 0.5% timolol maleate or the vehicles was started 2 days before surgery, and continued until 5 weeks after surgery. Diclofenac or fluorometholone drops were instilled in the eyes 4 times preoperatively, on the day of surgery, and 3 times daily for 5 weeks postoperatively.

RESULTS

The flare amount was higher on the third and seventh days in group B than in group D, but was the same after the seventh day. The incidence of angiographic CME was the same between both groups. These 2 factors were significantly lower in group F. These 2 factors were also significantly lower in the 3 groups that received diclofenac instead of fluorometholone, with no difference among these groups. The intraocular pressure decline was significant in groups that received timolol compared with groups that received PV or NPV.

CONCLUSIONS

Timolol and its preservative, benzalkonium chloride, cause disruption of the blood-aqueous barrier in early postoperative pseudophakia and increased incidence of angiographic CME. The concurrent administration of nonsteroidal anti-inflammatory drug such as diclofenac prevents these adverse effects without interfering with the drop in intraocular pressure caused by timolol. The addition of benzalkonium chloride to timolol contributes considerably to these adverse effects.

CLINICAL RELEVANCE

The present results suggest the cause of similar complications produced by other antiglaucoma eyedrops containing similar preservatives.

Treatment of retinal detachment resulting from myopic macular hole with internal limiting membrane removal

PURPOSE

To examine the efficacy of vitrectomy with internal limiting membrane removal for retinal detachment resulting from a macular hole in highly myopic eyes.

METHODS

Eleven consecutive highly myopic eyes (11 patients) with retinal detachment resulting from a macular hole were treated by vitrectomy with removal of the internal limiting membrane, which was stained with indocyanine green and sulfur hexafluoride gas injection. Postoperatively, the patients were instructed to remain prone for 2 weeks. The excised specimens were evaluated with transmission electron microscopy.

RESULTS

The mean postoperative follow-up was 9.2 +/- 2.3 months (range, 7 to 13 months). In 10 of the 11 eyes (91%) the retina was reattached during the initial surgery. Redetachment occurred in one eye, which was successfully treated during the second surgery. Best-corrected visual acuity improved in all eyes and ranged from 20/400 to 20/50. Pathologic examination showed that the internal limiting membrane and epiretinal tissues were present in all specimens.

CONCLUSIONS

The use of indocyanine green staining can facilitate removal of a macular internal limiting membrane and overlying epiretinal membrane, resulting in complete relief of the macular traction. Primary removal of the internal limiting membrane may contribute to a high initial success rate for retinal reattachment and be an important adjuvant to the treatment of retinal detachment resulting from a macular hole in highly myopic eyes.

Guided knives

A new type of knife that enables a surgeon to easily create tunnel-shaped incisions with a prescribed depth has been developed. The knife features an incision guide, the arm of which extends just beyond the tip of the blade. The space between the blade and the arm can be set at the desired width. By moving the knife as if sliding the arm across the corneal or scleral surface, the blade can move to a certain depth from the surface. The guided knife enables even novice surgeons to easily make a self-sealing incision during cataract surgery. In addition, the innovative nature of this device seems to be applicable to many other surgeries that require a partial-thickness incision.

Iris neovascularization after vitrectomy combined with phacoemulsification and intraocular lens implantation for proliferative diabetic retinopathy

PURPOSE

To analyze the incidence of iris neovascularization after vitrectomy combined with phacoemulsification and intraocular lens (IOL) implantation using a small incision in the treatment of proliferative diabetic retinopathy (PDR).

PATIENTS AND METHODS

We studied a consecutive series of 46 eyes in which vitrectomy combined with phacoemulsification and IOL implantation had been performed, and compared the surgical results with a prior series of 40 eyes in which vitrectomy alone had been performed.

RESULTS

Postoperative iris and angle neovascularization was found in 6 eyes (15%) treated by vitrectomy alone, but in only 1 eye (2%) treated by combined vitrectomy (P<0.05). Final visual acuity improved by two or more lines in 23 eyes (57%) in the vitrectomy alone group, and in 35 eyes (76%) in the combined vitrectomy group.

CONCLUSIONS

The incidence of postoperative rubeosis iridis was significantly lower, and the visual results were satisfactory with vitrectomy combined with phacoemulsification and IOL implantation for PDR. These findings suggest that combined vitrectomy for PDR is a useful surgical procedure.

Controlling astigmatism in cataract surgery requiring relatively large self-sealing incisions

PURPOSE

To evaluate the results of a modified self-sealing incision for achieving astigmatic neutrality in cataract surgery requiring a 6.0 to 7.0 mm incision as well as the methods of correcting preexisting astigmatism using these incisions.

SETTING

Department of Ophthalmology, Kushimoto Rehabilitation Center, Kushimoto, Japan.

METHODS

To achieve astigmatic neutrality, a frown-shaped, oblique incision-the BENT (between 9 and 12 o'clock) frown-was used. To reduce preexisting against-the-rule or with-the-rule astigmatism, the incisions were placed on the temporal or superior steep astigmatic axis, respectively. A frown incision was used when aiming for mild astigmatic reduction and an arcuate incision when aiming for relatively large astigmatic reduction.

RESULTS

In the 6.0 to 7.0 mm BENT frown incision group, mean flattening was minimal throughout 6 months of follow-up, with a maximum of 0.18 diopter (D) 1 week postoperatively. Surgically induced astigmatism was less than that with other incisions. Ninety-four percent of cases had a difference in absolute astigmatism of less than 0.50 D between preoperatively and 6 months postoperatively. Relatively large flattening was observed in eyes with 6.0 to 7.0 mm steep-axis incisions of superior arcuate, temporal arcuate, superior frown, and temporal frown, with means of 1.03, 0.79, 0.64, and 0.52 D, respectively, at 6 months. Ninety-eight percent of cases had a reduction in preexisting absolute astigmatism postoperatively.

CONCLUSIONS

In cataract surgery using relatively large scleral self-sealing incisions, the BENT frown incision effectively achieved astigmatic neutrality. The incisions on the temporal or superior steep astigmatic axis (with selective shape) reduced astigmatism in almost all cases.

Quarters extraction technique for manual phacofragmentation(1)

In the quarters extraction technique, the nucleus is manually split and the fragments then removed. A 5.5 to 6.5 mm sclerocorneal single-plane incision is made. After capsulorhexis, hydrodissection, hydrodelineation, and surface cortex aspiration, the edge of the nucleus is prolapsed into the anterior chamber. The front quarter of the nucleus is cut and removed with a nucleus puncher. A corner of the remaining three quarters of nucleus is wedged into the wound and rotated out with a claw vectis. Among the initial 120 cases, there were no posterior capsule ruptures, and the mean endothelial cell loss at 3 months was 8.7% +/- 6.5% (SD). Because there is no need to deeply insert instruments at the time of nuclear fragmentation, this technique can be performed safely and easily in most cases except in eyes with very large nuclei.

Manual sutureless cataract surgery using a claw vectis

Two-handed sandwich methods of extracapsular cataract extraction using a self-sealing incision have proved difficult for many inexperienced surgeons. We developed a simpler 1-handed technique using a claw vectis-a vectis with a claw placed on its tip. When the nucleus is pulled through the scleral tunnel, it is fixed by the claw and is smoothly removed from a wound of a size comparable to that in the sandwich method. During nucleus removal, viscoelastic material is constantly injected through the irrigation vectis to maintain the anterior chamber depth, resulting in a low incidence of complications. We have performed 620 cases using the technique and found it safe and easy for both novice and experienced surgeons.

Analysis of liquid accumulated in the distended capsular bag in early postoperative capsular block syndrome

PURPOSE

To analyze the transparent liquid between the posterior lens capsule and the posterior chamber intraocular lens (PC IOL) in early postoperative capsular block syndrome and discuss the mechanism of posterior capsule distention.

SETTING

Department of Ophthalmology, Tokyo University School of Medicine, and Tokyo Research Institute, Seikagaku Corporation, Tokyo, Japan.

METHODS

This study evaluated 3 cases of capsular block syndrome presenting with transparent liquid in the distended capsular bag 1 day after cataract surgery. The transparent liquid material between the posterior capsule and PC IOL was aspirated and analyzed using high-performance liquid chromatography (HPLC). Also, sodium hyaluronate was diluted using a dialyzer to determine whether the aqueous humor was drawn into the capsular bag by an osmotic gradient across the capsule.

RESULTS

The elution time of the samples was almost the same as that of sodium hyaluronate 1.0% (Healon) The concentration of the samples ranged from 3.29 to 9. 01 mg/mL by HPLC analysis. The sodium hyaluronate absorbed the physiological salt solutions through the dialyzer and expanded to 1. 9 times its original volume.

CONCLUSIONS

These results indicate that the main ingredient of the transparent liquid in capsular bags is sodium hyaluronate and that the distention is caused by aqueous humor being drawn into the capsular bag by an osmotic gradient across the capsule when the capsulorhexis diameter is smaller than that of the PC IOL and by viscoelastic material retained and trapped in the bag intraoperatively.

A new concept for the correction of astigmatism: full-arc, depth-dependent astigmatic keratotomy

OBJECTIVE

The purpose of this study is to introduce and evaluate a new concept in astigmatic keratotomy (AK) named full-arc, depth-dependent AK (FDAK).

DESIGN

Noncomparative interventional case series.

PARTICIPANTS

FDAK was performed on a total of 37 eyes with regular astigmatism; of these, 16 eyes received FDAK alone, and 21 eyes received FDAK combined with cataract surgery.

METHODS

Corneal topography was used to divide the cornea into two discreet regions of "steep" and "flat." Then, paired arcuate incisions, 90 degrees in length, were placed along the full arc of the steep area. The level of astigmatic correction was controlled by varying the incision depth from 40% to 80% on the basis of a provisional nomogram developed by the authors.

MAIN OUTCOME MEASURES

Keratometries, corneal topographies, and visual acuities were measured.

RESULTS

The FDAK alone group showed a significant improvement from a preoperative corneal astigmatism of 2.90 +/- 0.78 diopters (D) to a postoperative value of 0.89 +/- 0.52 D. The "combined" group also showed significant improvement from a preoperative corneal astigmatism of 2.97 +/- 1.01 D, to a postoperative value of 1.02 +/- 0.45 D. The deviation of achieved correction from attempted correction using vector analysis was between 1.37 D of undercorrection and 0.98 D of overcorrection, with 91.9% of cases within the range of +/- 1.0 D. Slight oblique change caused by axis deviation was observed in seven cases. Both uncorrected and corrected visual acuity showed statistically significant improvement. No serious complications were encountered.

CONCLUSIONS

Controlling the level of correction by varying the incision depth allowed the surgeon to use long incisions (90 degrees in length in regular astigmatism) covering the entire steep area, minimizing the undesirable changes induced by conventional deep and narrow incision AK and resulting in an ideal corneal sphericity after surgery. FDAK enabled the surgeon to accurately control the level of astigmatic correction with minimal risk of corneal perforation.