Intrastromal corneal ring segments for low myopia: a report by the American Academy of Ophthalmology.

OBJECTIVE: This document describes intrastromal corneal ring segments (Intacs) inserts technology and examines the evidence to answer the key question about whether the treatment is safe and effective in correcting low myopia. METHODS: A literature search that was conducted in September 2000 retrieved 13 relevant citations, and the reference lists of these articles were consulted for additional citations. Panel members reviewed this information and articles were rated according to the strength of evidence. RESULTS: Prospective multicenter phase II and III clinical trials (Level II evidence rating) of Intacs inserts for myopia of -1.00 to -3.00 diopters (D), with a maximum of +1.00 D of astigmatism, enrolled a total of 452 subjects, with a total of 454 surgical attempts. The results from phase II and phase III were pooled for much of the analysis. At 1 year, 97% of patients who completed follow-up had 20/40 or better uncorrected visual acuity (UCVA). Seventy-four percent of patients had 20/20 or better UCVA. Ninety-two percent of eyes were within +/-1 D of intended refractive correction, and 69% were within 0.5 D of intended refractive correction. At 3 months, 90% of patients had less than 1.0 D of change from the previous examination performed at 1 month. The ocular complication rate, which was defined as clinically significant events but not resulting in permanent sequelae, was 11% at 12 months. The adverse event rate was 1.1%, defined as a serious event if untreated. Nearly 9% of patients requested to have their inserts removed and a total of 3.8% of patients required a secondary surgical intervention. CONCLUSIONS: To date, evidence suggests that low myopia (-1 to -3 D) in a well-defined group of patients who have a stable manifest refraction and less than +1.0 D of astigmatism can be treated with Intacs inserts with a reasonable assurance of safety and effectiveness. Additional clinical research is needed to determine the long-term effectiveness of treatment and the comparative safety, effectiveness, and costs with other treatment modalities, including laser-assisted in-situ keratomileusis (LASIK) and photorefractive keratectomy (PRK).

Laser vision correction for low hyperopia. An 18-month assessment of safety and efficacy.

OBJECTIVE: This study aimed to assess the efficacy and safety of hyperopic photorefractive keratectomy (PRK) and to evaluate the effect of degree of hyperopia, two epithelial removal methods, and various postoperative patient management techniques on clinical outcomes. DESIGN: Prospective, nonrandomized, open-label clinical trial. PARTICIPANTS: A total of 38 patients with mean follow-up of 13.9 months (n = 65 eyes with hyperopia from +1.00 diopter [D] to +4.00 D) participated. INTERVENTION: Hyperopic PRK with the VISX STAR Excimer Laser System was performed. MAIN OUTCOME MEASURES: Spherical equivalent (SE) including vector analysis of SE; uncorrected visual acuity (UCVA); best-spectacle corrected visual acuity (BSCVA); low-, medium- and high-contrast visual acuities; topography; keratometry; pachymetry; and intraocular pressure, haze, and all other potential complications were measured. RESULTS: A total of 80% of eyes were within +/- 0.5 D and all but 1 eye (98%) were within +/- 1.0 D of intended manifest SE at 1 year. There was no induced astigmatism at 1 year. At 12 months, 72% of eyes had UCVA of 20/25 or better and 70% had achieved preoperative BSCVA, with no eye seeing worse than 20/25. These results remained constant at 18 months. There was a tendency toward regression between months 1 and 6 with stabilization of SEs between months 6 and 12. Thereafter, up to 18 months, there was some regression with a mean of +0.31 D, but the number of patients was small. There was one mild decentration and very slight decreases in mean intraocular pressure and central corneal thickness. One patient had grade 1.0 haze develop in both eyes at 12 and 18 months; all other patients experienced trace or no haze. There were no significant complications. CONCLUSIONS: The results of this study support the hypothesis that laser vision correction is safe and effective for treating low hyperopia. The predictability of the hyperopic laser vision correction procedure used in this study was very good. Other than the slower recovery of BSCVA and UCVA seen with this procedure, as compared with myopic PRK, there were no significant complications. The trend toward some later regression needs to be further evaluated in a larger number of patients. Overall, patients were very pleased with the treatment, even in the first 6 months.

Evaluation of current techniques of corneal epithelial removal in hyperopic photorefractive keratectomy.

PURPOSE: To determine the efficacy of 3 current methods used to remove corneal epithelium prior to photorefractive correction of hyperopia and to compare clinical data in patients who had rotary brush or blunt scrape epithelial removal in the treatment of hyperopic photorefractive keratectomy (PRK). SETTING: University of Ottawa Eye Institute, Ottawa General Hospital, Ottawa, Ontario, Canada. METHODS: The epithelium from human eye-bank eyes was removed using a Paton spatula, 15% alcohol, and the Amoils rotating plastic brush. The effects were examined by scanning and transmission electron microscopy. Twelve month postoperative data were obtained on 25 eyes with refractions of +1.00 to +4.00 diopters (D) that had been treated for hyperopia with the VISX Star excimer laser, using blunt scrape or the rotary brush to remove the corneal epithelium. RESULTS: All 3 methods effectively removed corneal epithelium. The Paton spatula, however, left small nicks in Bowman's layer. Both the rotating brush and alcohol debridement left Bowman's layer intact. Alcohol treatment required follow-up epithelial debris removal, while brushing left minimal amounts of debris. There was a strong trend toward rapid epithelial healing in the brushed corneas compared with the scraped ones, but this was not statistically significant. Clinically, at 12 months postoperatively, brushed corneas showed a trend toward more superior outcomes than scraped corneas in actual refractive outcome, uncorrected visual acuity (UCVA), lines of UCVA gained, and predictability of the desired outcomes. However, only the outcome in UCVA of 20/40 or better and the decreased incidence of haze in the brushed corneas over scraped ones were statistically significant. CONCLUSIONS: Both alcohol and the rotating brush provide a quick, effective means of removing the corneal epithelium with minimal risk of damage to Bowman's layer. In our experience, the brush technique was as effective as and possibly superior to the blunt scrape for epithelial removal in hyperopic PRK.

Correction of intraocular pressure for changes in central corneal thickness following photorefractive keratectomy.

OBJECTIVE: To investigate the relation between measurements of intraocular pressure (IOP) and central corneal thickness (CCT) in myopic patients undergoing photorefractive keratectomy (PRK). DESIGN: Descriptive study. SETTING: University-affiliated eye care centre in Ottawa. PATIENTS: A total of 481 consecutive eyes of 318 patients with a mean preoperative refractive error of -6.50 dioptres treated with excimer PRK between March 1993 and December 1996. OUTCOME MEASURES: IOP measured by Goldmann applanation tonometry and CCT before and 3, 6, 12, 18 and 24 months after surgery. RESULTS: CCT was a significant predictor of IOP only before PRK and 6 months after PRK (p < or = 0.05). The relation between IOP and CCT suggests corrections for CCT that are not clinically significant (0.81 mm Hg [standard error (SE) 0.33 mm Hg] and 1.00 mm Hg [SE 0.38 mm Hg] per 100 microns of corneal thinning preoperatively and at 6 months respectively). On average, there was a significant decrease in IOP after PRK (0.96 mm Hg and 1.24 mm Hg at 12 and 24 months respectively) (p < 0.05). There was a significant correlation between change in IOP and change in CCT (decrease of 2.1 mm Hg per 100 microns of corneal thinning) (p < 0.05). For a given change in CCT, individual changes in IOP were variable, with increases or decreases of more than 5 mm Hg in some cases. CONCLUSIONS: There are individual differences in IOP changes following PRK. Until further data are available we propose that the change in IOP between the preoperative visit (or the fellow eye, if healthy or untreated) and the 12-month visit be used as an individual correction factor to be applied to IOP measurements in the operated eye.

Excimer laser photorefractive keratectomy for low hyperopia: safety and efficacy.

PURPOSE: To assess the safety and efficacy of photorefractive keratectomy (PRK) to correct low hyperopia. SETTING: University of Ottawa Eye Institute, Ottawa General Hospital, Ontario, Canada. METHODS: Twenty-five eyes with refractions of +1.00 to +4.00 diopters (D) and cylinder of 1.00 D or less were treated for hyperopia with the VISX Star excimer laser system using a refined ablation architecture. Thorough visual assessments were performed preoperatively (baseline) and 1, 3, and 6 months postoperatively. Complications were recorded and the level of patient satisfaction was noted. RESULTS: Mean spherical equivalent at 6 months was +0.27 D +/- 0.55 (SD), which was an 89% reduction over baseline. Eighty-four percent of patients gained two to seven lines of near uncorrected visual acuity (UCVA) and 1 patient (4%) lost more than one line. Eight percent achieved 20/25 or better UCVA. Approximately half realized their preoperative distance best corrected visual acuity (BCVA) by 1 month. By the end of the study, all patients had improved, achieved, or were within one line of their baseline distance BCVA. There were some slight reductions in lower contrast acuity at 6 months, although dim lighting conditions did not further reduce these acuities. Most patients had no clinically meaningful change in cylinder. The most common complications included early, transient corneal surface irregularities and visual symptoms and trace haze (grade < or = 0.5) in 14 of 23 patients at 6 months. All but 1 patient expressed a high degree of satisfaction. CONCLUSIONS: These results support the hypothesis that PRK shows great promise as a safe and effective treatment for low hyperopia. There were no significant complications and no decentered ablations. The slight regression occurred with or without the presence of trace haze. Overall, refractive stability was encouraging, although longer follow-up is needed.

Ocular findings in acromesomelic dysplasia.

We examined an infant who had prenatal onset of a skeletal dysplasia that had many features in common with acromesomelic dysplasia, including the clinical and light and electron microscopic findings of both corneas. Successful lamellar keratoplasty was performed on the left eye when histologic examination of the corneal button from the right eye showed that the corneal scar was only of partial thickness.

Effects of insulin and EGF on DNA synthesis in bovine endothelial cultures: flow cytometric analysis.

PURPOSE: To investigate the effects of insulin, epidermal growth factor (EGF), and the corneal storage media--DexSol--at 24 and 48 hours on DNA synthesis in confluent primary cultures of bovine corneal endothelial cells. METHODS: Flow cytometry was used to measure changes in DNA synthesis. This technique allows a large number of cells to be counted and sorted into G1, S, and G2/M phases of the cell cycle. RESULTS: Changing the normal culture media to DexSol had no effect on the cell cycle at 24 or 48 hours. The addition of insulin, EGF, or insulin + EGF to DexSol increased DNA synthesis within 24 hours. The mitotic indices for DexSol, DexSol + insulin, and DexSol + EGF were 0.134 (SE = +/- 0.022), 0.207 (+/- 0.027), and 0.205 (+/- 0.052), respectively. Adding insulin + EGF to the DexSol resulted in the most significant change in S and G2/M, increasing the mitotic index to 0.300 (+/- 0.072) (P = 0.0116). At 48 hours, the presence of the growth factors no longer had any effect. CONCLUSIONS: Flow cytometry was a useful technique in separating cultured bovine corneal endothelial cells according to their DNA content. Analysis of the cultures after the addition of insulin and EGF showed an increase in DNA synthesis. The synergistic effects of the growth factors on corneal endothelial cells suggest that they stimulate mitotic activity by different mechanisms. The addition of mitogens to eye bank storage media may increase corneal endothelial cell densities in donor corneas.

Four-incision radial keratotomy for high myopia after penetrating keratoplasty.

BACKGROUND: High amounts of myopia can frequently produce anisometropia and limit visual rehabilitation by conventional means in eyes with clear corneal grafts. This condition is frequently coupled with large amounts of astigmatism. Four-incision radial keratotomy provides a way to reduce myopia in normal individuals. In our present study, we used the technique of four- incision radial keratotomy to reduce myopia in a group of keratoplasty patients who failed conventional visual rehabilitation. Arcuate or transverse keratotomy was used in conjunction with radial keratotomy in eyes with high amounts of astigmatism. METHODS: This study retrospectively examined a group of 11 eyes with penetrating keratoplasty which underwent four-incision radial keratotomy for the treatment of visually disabling myopia. The radial incisions were placed in the graft, inside the graft-host interface. Seven eyes underwent concomitant arcuate relaxing incisions at the graft-host interface for treatment of associated astigmatism. One additional eye had paired straight transverse incisions for the treatment of astigmatism. The mean postoperative follow up was 16 months (range, 3 months to 5 years). RESULTS: There was a mean reduction of the spherical equivalent refraction of 3.48 diopters (D) (range, 0.25 to 7.75 D). The eight eyes undergoing astigmatic surgery showed a mean reduction in keratometric astigmatism of 2.25 D (range, -6.75 to +6.50 D) and refractive astigmatism of 4.63 D (range, -1.50 to -9.50 D). Nine of the 11 eyes had stable or improved best spectacle corrected visual acuity. Two eyes had reduction of best spectacle corrected visual acuity--one due to development of irregular astigmatism and one due to worsening of preexisting macular edema. CONCLUSIONS: Four-incision radial keratotomy can reduce myopia after penetrating keratoplasty when the patient is unable to tolerate spectacle or contact lens correction. It can be combined with relaxing incisions or transverse keratotomy to reduce astigmatism. There is a high amount of variability, and predictability is currently limited by the complex topographical changes occurring in corneal transplants. Complex corneal biomechanical changes may predispose these eyes to the development of irregular astigmatism.

Cataract surgical techniques.

Cataract surgery continues to evolve as modifications in techniques are introduced. Extracapsular surgery, whether by phacoemulsification or planned extracapsular cataract extraction, is a very safe and effective technique. Maintaining versatility in operative techniques, depending on the clinical situation, is a distinct challenge for the cataract surgeon. Adequate surgical planning, coupled with meticulous surgical technique, gives optimal results. Innovations in wound architecture provide intraoperative and postoperative advantages to the surgeon and to the patient. Capsulorhexis is the preferred method of capsulotomy in phacoemulsification and planned extracapsular cataract extraction. Hydrodissection and related techniques are useful in all types of extracapsular cataract extraction. This article reviews techniques in cataract surgery with an emphasis on the recent literature.

Cataract surgical techniques and adjuncts.

The ophthalmologist performing cataract surgery today has a wide variety of options in terms of both surgical technique and available surgical adjuncts, which can greatly enhance the results of cataract surgery. Surgical adjuncts used both preoperatively and intraoperatively include mydriatics, pupil maintainers, oculopressor devices, viscoelastics, and intraocular irrigating solutions. Cataract surgical techniques continue to evolve, and phacoemulsification continues to increase in popularity. Hydrodissection and related techniques have become an important part of all types of extracapsular cataract surgery. In this article, we review cataract surgical techniques and the use of surgical adjuncts with an emphasis on the recent literature. Modifying surgical techniques to incorporate new developments and thus enhance results remains a distinct challenge to the ophthalmic surgeon.

Cataract surgical techniques.

Cataract surgical techniques are constantly evolving and changing, offering the ophthalmologist new and sometimes improved options for optimal visual rehabilitation of their patients. This article reviews the surgical techniques used in cataract surgery with an emphasis on the recent literature. The following areas are covered: anesthesia, incisions and wound closure, capsulotomy, planned extracapsular cataract surgery, phacoemulsification, intraoperative management of the torn posterior capsule, trauma, and combined procedures. The use of phacoemulsification continues to increase in popularity in the developed countries. Small incisions for cataract surgery hasten visual rehabilitation, and continuous circular capsulorhexis has emerged as an advantageous capsulotomy technique. With proper intraoperative management, patients with torn posterior capsules have excellent visual results. Combined procedures allow for concurrent surgery in patients with cataract and coexistent ocular diseases. Cataract surgical techniques must be adapted to suit each patient. The modification of surgical techniques according to individual patient needs and associated ocular and systemic disorders offers a distinct challenge to the ophthalmic surgeon.

Transscleral fixation of posterior chamber intraocular lenses in the absence of capsular support.

We present results obtained by transscleral ciliary sulcus fixation of posterior chamber intraocular lenses in secondary implantation, lens exchange, and in primary implantation of transsclerally fixated lenses during complicated cataract extraction. Follow-up data on 38 patients, 17 of whom have been followed for more than 12 months, are included. We conclude that the procedure is safe, effective, and predictable.

Anatomic study of transsclerally sutured intraocular lens implantation.

We used 21 cadaver eyes to study transsclerally sutured, ciliary sulcus-fixated intraocular lens implantation. Results showed that transscleral sutures should exit the sclera less than 1 mm posterior to the corneoscleral limbus for true ciliary sulcus fixation. The relationship of the ciliary sulcus to the overlying posterior surgical limbus differed in the vertical and horizontal meridians; needles that pierced the ciliary sulcus after being passed perpendicularly through the sclera entered the sclera 0.83 +/- 0.1 mm posterior to the posterior surgical limbus in the vertical meridians and 0.46 +/- 0.1 mm in the horizontal meridians. The major arterial circle of the iris (located in the ciliary body) was avoided as was the entire ciliary body during proper ciliary sulcus fixation. A one-piece, all polymethylmethacrylate, 10-degree vaulted, 13.5-mm haptic spread intraocular lens provides excellent optic centration and haptic stabilization when the haptic structure is placed at the greatest haptic spread and one transscleral suture pass per haptic is made.

Transcleral ciliary sulcus fixation of posterior chamber intraocular lens implants.

We present our results of transcleral ciliary sulcus fixation of posterior chamber intraocular lens implants (IOL) in IOL exchange cases, secondary implants, and complicated cataract extractions. Follow-up data are presented on a total of 19 patients. The technique is facilitated by using a long needle attaching 10-0 prolene suture to both haptics of an all polymethylmethacrylate (PMMA) posterior chamber intraocular lens implant (PCL). Our early results show that the procedure is safe and predictable.

Nocardia asteroides keratitis associated with extended-wear soft contact lenses.

Chronic unilateral keratitis developed in a 34-year-old woman who wore extended-wear contact lenses. A clinical response was not obtained until Nocardia asteroides was correctly identified as the causal agent. The response to 30% sulfacetamide was dramatic. We review the clinical presentation of Nocardia keratitis and recommendations for management. Use of corticosteroids should be avoided in Nocardia keratitis. This opportunistic organism should be considered in patients who wear contact lenses in whom infectious keratitis develops.

Analysis of astigmatic keratotomy.

Eighty-two keratotomy procedures were performed for both idiopathic and postsurgical astigmatism or myopic astigmatism and analyzed for efficacy using vector and linear regression analysis. Delta keratometry values (delta K) were computed for each case as delta K in the desired axis of effect using vector analysis. Six different procedures were compared including both intersecting and nonintersecting trapezoidal keratotomy, relaxing incisions with compression sutures, T cuts with radial keratotomy, T cuts alone, and RK with elliptical optical zones. Our results showed that the greatest shifts occurred in the trapezoidal groups, whereas the most predictable effects occurred in the relaxing incision/compression suture group. Astigmatic keratotomy is capable of producing large shifts in corneal astigmatism; however, the accuracy of these procedures remains highly variable.

Traumatic hyphema in children.

The authors reviewed the medical records of 316 children admitted between January 1977 and March 1985 with a diagnosis of traumatic hyphema. In this group of patients, 1 to 17 years old treated without antifibrinolytics, the incidence of secondary hemorrhage was 7.6% (24 of 316 patients) of whom three required surgical evacuation of the clot. The risk of rebleeding did not correlate with the patient's age, use of topical steroids, or cycloplegics. Of 176 patients followed from 1 month to 7 years post-hospital discharge, 91% achieved 20/30 vision or better, but only 77% of the patients with secondary hemorrhage attained this level of vision. Amblyopia, a potential threat in young children, occurred in only two children both of whom also required cataract extraction. From our captive pediatric population of 228,000 the incidence of traumatic hyphema is 17 per 100,000 children per year.