Effect of incision direction on refractive outcome after radial keratotomy

PURPOSE: To determine whether the direction of radial keratotomy (RK) incisions (centripetal versus centrifugal) affects refractive outcome. SETTING: Private ophthalmology office. METHODS: The database of a single surgeon was retrospectively reviewed. Stepwise regression was used to select significant predictors of refraction change in the population. In addition to incision direction, variables evaluated were optic zone diameter, number of incisions, patient age, corneal curvature, and planned incision depth. RESULTS: All variables except planned incision depth and corneal power affected refractive outcome. After controlling for number of incisions, optic zone diameter, and patient age, centripetal incisions decreased myopia 0.87 diopters more than centrifugal incisions. CONCLUSIONS: Our results, consistent with previous investigations, found that number of incisions, optic zone diameter, and patient age were significant predictors of refractive outcome after RK. Incision direction was also a significant predictor by itself or coupled with optic zone diameter and number of incisions, with the centripetal incision decreasing myopia more.     

Inhibition of cathepsin B by its propeptide: use of overlapping peptides to identify a critical segment

OBJECTIVE: The study was designed to investigate the corneal changes at various times after epikeratophakia performed on rabbit cornea. METHODS: The process of epithelial repair, or interlayer healing, the changes of endothelial cells and Langerhans cells (LC) in corneal epithelium were observed at different intervals after surgery by using histochemistry technique. RESULTS: The epithelial repair of the graft was completed by 4-12 postoperative days. The repopulation of keratocytes was seen firstly at peripheral and superior part of the lenticule at 7-14 postoperative days and completed to normal by postoperative 2 months. No changes were observed in the endothelial cells. The proliferation of LC was observed in the limbal epithelium at day 3, reached the peak by day 14 and recovered to normal at month 2 postoperatively. CONCLUSION: Epikeratophakia is available and safe, The proliferation of LC might result from wound healing not from immune rejection.     

Erythrophagocytic tumour cells in melanoma and squamous cell carcinoma of the skin

BACKGROUND: Radial keratotomy may induce late hyperopic shift. We present data on 140 consecutive eyes with a follow-up of up to 3 years that underwent radial keratotomy with the RK suction bridge. METHODS: We conducted a retrospective study of 140 consecutive eyes that had radial keratotomy between 1987 and 1994. Mean preoperative spherical equivalent was -5.21 D (range -2.00 to -9.75 D). All operations were performed by one surgeon (JHK) with the RK suction bridge. A suction ring maintaining physiological intraocular pressure immobilized the eye and left a peripheral rim of uncut cornea. The ring incorporated an eccentric bridge that guided the radial keratotomy knife. The knife setting was 90% of the central corneal thickness, measured by pachymetry. Spherical equivalent refraction and spectacle corrected visual acuity were measured at 1 week, 1, 3, 6 months, 1 year, and 3 years after radial keratotomy. RESULTS: The mean preoperative spherical equivalent refraction of -5.21 D dropped to -0.43 D at 1 week (n = 136), -0.71D at 1 month (n = 120), -0.85 D at 3 months (n = 95), -0.74 D at 6 months (n = 73), -0.77 D at 12 months (n = 79), and -0.85 D at 3 years (n = 67). Compared to 1 month spherical equivalent, at 3 years three eyes (4.4%) had moved > = or 1.00 D toward hyperopia. One eye (1.4%) shifted by 1.25 D. Paired t-tests of mean spherical equivalent refraction did not reveal significant shifts toward hyperopia. Mean preoperative spectacle-corrected visual acuity was slightly diminished at 1 week and was equal or better thereafter. CONCLUSIONS: Our 3-year data suggest that a late hyperopic shift following radial keratotomy may be prevented if an intact peripheral rim is maintained and cutting depth does not exceed 90% of the lowest corneal thickness.     

Natural history of corneal topography after excimer laser photorefractive keratectomy

PURPOSE: To investigate the natural history of corneal topography after excimer laser photorefractive keratectomy (PRK). DESIGN: A prospective, single center clinical study. PARTICIPANTS: A total of 40 eyes of 34 patients with myopia were studied. INTERVENTION: Excimer laser photorefractive keratectomy and computer-assisted videokeratography were performed. MAIN OUTCOME MEASURES: Preoperative, 1 week, and 1, 2, and 3 months postoperative topography patterns were compared and changes assessed by averaging defined sectors of the ablation zone in individual maps to produce composite "average" topography maps. RESULTS: Corneal topography was generally not homogeneous at 1 week after PRK. By 3 months, there had been considerable smoothing of corneal contour. A general "central island" effect early in the postoperative period flattened over time. When right and left eyes were evaluated independently, a tendency toward a keyhole-semicircular pattern was seen on average; the maximum flattening was nasal and the least flattening was inferotemporal for both right and left eyes. CONCLUSIONS: A tendency, on average, toward central island and keyhole-semicircular patterns is seen early in the postoperative course after PRK. Central islands tend to evolve into the keyhole-semicircular pattern, and the corneal topography in general after PRK tends to smooth considerably with time.     

Arcuate keratotomy to correct naturally occurring astigmatism

PURPOSE: To evaluate retrospectively the safety, efficacy, and complications of arcuate keratotomy (AK) in correcting naturally occurring astigmatism. SETTING: Laser Ultravision Institute, Montreal, Canada. METHODS: Surgically induced refractive change was evaluated in 25 eyes of 15 patients with naturally occurring astigmatism. All patients had mixed or compound myopic astigmatism and were treated with AK alone or both AK and radial keratotomy (RK). Minimum follow-up of 24 months was necessary for inclusion in this study. We used vector analysis to evaluate the refractive and keratometric astigmatic change at 1 month and 1 and 2 years. RESULTS: Ten eyes (40%) had AK only and 15 eyes (60%), both AK and RK. It was necessary to redeepen the original incisions in 21 eyes (84%). All patients had improved uncorrected visual acuity postoperatively. The reduction in refractive cylinder, quantified by vector analysis, was significant. Two years postoperatively, mean reduction was 3.30 diopters (D) +/- 1.32 (SD) in eyes that had AK alone and 2.71 +/- 1.53 D in eyes that had both AK and RK. CONCLUSION: Arcuate keratotomy is an effective and safe method for correcting naturally occurring astigmatism. Further analysis of this series of patients is planned.     

Further study of hepatitis C virus RNA detection in formalin-fixed, paraffin-embedded liver tissues by ligation-dependent polymerase chain reaction

AIM: Refractive cataract surgery using corneal incisions is aiming at neutralization of preoperative astigmatism. PATIENTS AND METHODS: 61 patients with preoperative astigmatism of 2.25 +/- 0.98 were included in the treatment. A self-sealing corneal tunnel incision measuring 4.0 to 4.1 mm in external diameter and 6.5 to 7.0 mm in internal diameter (stretch incision) was performed on the steeper axis. After capsulorhexis and phacoemulsification a 5 mm PMMA lens was implanted without suturing. Keratometry and corneal topography were performed preoperatively, 3 days and 1 year respectively following surgery. The statistical analysis was based on the Wilcoxon signed ranks test. RESULTS: Surgical induced astigmatism (IA) following superior incisions in cases of astigmatism with the rule (n = 29) amounted to 1.93 +/- 0.97, while lateral incisions in cases of astigmatism against the rule (n = 29) led to an IA of 1.35 +/- 0.73. Axial shifts by more than 30 degrees were 23% following superior incisions and 17%, after lateral incisions. We observed. astigmatic reduction of 1.3 D after superior incisions and 0.7 D following lateral incisions. CONCLUSION: By 4 mm corneal cataract incisions on the steeper axis a high preoperative astigmatism can be reduced significantly without additional keratotomies.     

Corneal astigmatism after clear corneal and corneoscleral incisions for cataract surgery

PURPOSE: To compare the astigmatism induced by clear corneal incisions (CCIs) and corneoscleral tunnel incisions (CSIs) for cataract surgery over 6 months. SETTING: Rotterdam Eye Hospital, rotterdam, The Netherlands. METHODS: Thirty-five patients having phacoemulsification were recruited prospectively; 15 had CCIs and 20, CSIs. Corneal topography was performed by computerized videokeratoscopy preoperatively and 6 months postoperatively. The change in keratometric astigmatism was calculated using the absolute magnitude and vector analysis methods. RESULTS: There was no significant difference between the change in astigmatism produced by the two incisions (Student's t-test). CONCLUSION: The CCI for cataract surgery did not produce significantly greater astigmatism than the CSI. Concern over CCIs having a greater risk of increasing corneal astigmatism is unfounded and does not justify withholding the technique from patients it could benefit.     

Endothelial study of iris-claw phakic lens: four year follow-up

PURPOSE: To study quantitative and morphometric endothelial changes in phakic eyes implanted with the Worst iris-claw lens to correct high myopia. SETTING: Department of Ophthalmology, University Hospital "La Fe", Valencia, Spain. MATERIAL AND METHODS: This retrospective study involved 111 phakic eyes (73 patients) implanted with the Worst iris-claw lens. Noncontact specular microscopy and computer-assisted analysis was performed preoperatively and 6 months and 1, 2, 3, and 4 years postoperatively. RESULTS: The mean cell loss was 3.85% at 6 months, 6.59% at 1 year, 9.22% at 2 years, 11.68% at 3 years, and 13.42% at 4 years. At 2 years, the hexagonality and coefficient variation in cell size were close to the preoperative levels. No major complications were seen; early postoperative corneal touch required intraocular lens (IOL) removal in 1 case (0.9%). Four eyes (3.6%) needed a reoperation because of poor IOL fixation (2 eyes), traumatic subluxation of the IOL (1 eye), and miscalculation of the IOL power (1 eye). CONCLUSIONS: Although there was a slight progressive cell loss after IOL implantation, the morphometric changes recovered and were close to the preoperative levels. This suggests that endothelial damage occurred primarily during the surgical procedure.     

Two-incision radial keratotomy for low myopia with astigmatism

PURPOSE: To evaluate the effectiveness of two-incision radial keratotomy (RK) in correcting low-magnitude refractive myopic astigmatism. SETTING: Two clinical study sites, one in St. Louis, Missouri, USA, the other in Caracas, Venezuela. METHODS: Fifty-seven eyes of 43 patients with low-magnitude myopic astigmatism had two-incision RK at one of two clinical study sites. In the initial phase of this series, 10 eyes with amblyopia at the 20/30 level had surgery at one center. Refractive keratotomy was performed with the radial incision placed in the plus cylinder axis of refraction. This axis was verified as the meridian of greatest corneal curvature by standard keratometry and computer-assisted corneal topographic analysis. Two eyes received a second operation (enhancement). RESULTS: Mean follow-up was 11.1 months (range 6 to 12 months). Mean preoperative and postoperative myopic spherical equivalent measured -1.42 diopters (D) +/- 0.51 (SD) and -0.14 +/- 0.39 D, respectively; the mean reduction was 1.28 +/- 0.59 D (P = .0001). Mean preoperative and postoperative refractive astigmatism was 1.41 +/- 0.45 D and 0.48 +/- 0.33 D, respectively (P = .0001). Mean preoperative and postoperative keratometric astigmatism was 1.26 +/- 0.54 D and 0.31 +/- 0.35 D, respectively, a mean reduction of 0.95 D (P = .0001). The surgical meridian was flattened by an average of 2.06 D by keratometry and the orthogonal meridian, by an average of 1.10 D. Preoperative uncorrected visual acuity (UCVA) was 20/40 or better in five (9%) eyes (range counting fingers to 20/40). Postoperative UCVA acuity was 20/40 or better in all eyes (mean acuity 20/25). In the nonamblyopic subgroup mean postoperative UCVA was 20/24. CONCLUSIONS: A limited number of radial incisions placed in the topographically confirmed axis of greatest curvature are effective in the treatment of low-magnitude myopic astigmatism.     

Transcendence: the meaning of great-grandmothering

OBJECTIVE: To investigate the wound healing of the cornea following 193 mm excimer laser photorefractive keratectomy (PRK) and the effects of corticosteroid on it. METHODS: PRK was performed on both eyes of 6 monkeys. Corticosteroid was given to the right eyes, but not to the left ones. At 4 days, 1 week, 2 weeks, 1 month, 3 months and 6 months, corneal pachymetry was examined and the eyes of one monkey were enucleated and the corneas were stained immunohistochemically for collagen type III, type IV and type VII, fibronectin and laminin. RESULTS: The expression of collagen type Vii recovered to the normal linear patter at 1 month. With corticosteroid, the deposition of collagen type III and fibronectin was markedly reduced and the pachymetry of central cornea was closer to the expected value. CONCLUSION: This study suggests that corticosteroid help to minimize the postoperative myopic regression and corneal haze after PRK.     

New results using Laue diffraction and time-resolved crystallography

PURPOSE: To determine the antiproliferative effect of minoxidil on human corneal epithelium (hCE) proliferation in vitro and to assess whether topical minoxidil can significantly alter corneal topography after radial keratotomy (RK) by inhibiting myofibroblast activity in the keratotomy wound. SETTING: Corneal Research Laboratory, University of Chicago, Illinois, USA. METHODS: In the in vitro evaluation, proliferating hCE was exposed to minoxidil (0.1 to 2.0 mM) for 96 hours to determine the minimum inhibitory dose. Human corneal epithelium cell proliferation was assessed by the incorporation of bromodeoxyuridine (BRDU) into DNA. In the in vivo analysis, eight New Zealand albino rabbits had an eight-incision bidirectional RK on one eye and were divided into two groups. The control eyes (n = 3) received tobramycin and dexamethasone (TobraDex), ciprofloxacin hydrochloride (Ciloxan), and balanced salt solution (BSS) drops four times a day for 3 weeks, while the treatment eyes (n = 5) received TobraDex, Ciloxan, and minoxidil 1.0 mM drops four times daily for 3 weeks. The net change in corneal curvature at 3 weeks was analyzed with corneal topography. Myofibroblast activity in the keratotomy wound was assessed using alpha smooth muscle actin staining techniques. RESULTS: At concentrations of 1.0 mM and above, minoxidil caused a statistically significant, dose-dependent reduction in hCE cellular proliferation ranging from 29 to 44% (P < .05). Minoxidil (1.0 mM) caused a statistically significant central corneal flattening effect of 4.66 diopters (D) after RK in the treatment eyes compared with 1.11 D in the control eyes (P = .05). Histologically, minoxidil-treated keratotomy wounds lacked cells with contractile elements consistent with myofibroblast differentiation. Corneal epithelial wound healing was similar in both groups. CONCLUSION: At the appropriate dose, topical minoxidil may be a useful adjunctive treatment that can reduce the number of undercorrections after mini-RK without apparent toxicity to the corneal epithelium.     

Wound healing following intrastromal photorefractive keratectomy with the Nd:YLF picosecond laser in the cat

BACKGROUND: We studied the histopathology of the stromal wound healing response in the cat cornea following intrastromal photorefractive keratectomy (IPRK) with the Nd:YLF picosecond laser. METHODS: Intrastromal PRK was performed in the anterior stroma of cat corneas with the Nd:YLF picosecond laser. The cats were sacrificed at predetermined intervals ranging from immediately to 6 months postoperatively. Effects of the laser treatment on the epithelium, Bowman's layer, stroma, and the endothelium were evaluated using light and scanning electron microscopy. No anti-inflammatory agents were used. RESULTS: Intrastromal PRK resulted in no perceptible damage to the corneal epithelium or Bowman's layer either acutely or at 6 months. The corneal stroma showed multiple cavitations immediately after intrastromal PRK, which collapsed over several hours, followed by thinning of the cornea over 2 weeks. At 1 month, the stromal collagen was abnormal with surrounding hypercellularity. The endothelium showed no injury, acutely or at 6 months. No thermal effects on stromal collagen were observed at 6 months, and disruption of the lamellar pattern was not apparent after the cavitation bubbles were reabsorbed. CONCLUSION: Intrastromal PRK can effectively remove stromal tissue without acute damage to the adjacent lamellae, epithelium, or endothelium. There is a transient cellular wound healing response associated with a transient stromal collagen abnormality at 2 weeks to 1 month, which was not apparent 2 months after the procedure.     

In vitro and in vivo evaluation of the enhancing activity of glycyrrhizin on the intestinal absorption of drugs

PURPOSE: To describe a surgical technique to visualize the depth of corneal incisions and lamellar stromal dissections during surgery. METHODS: In porcine cadaver eyes, the aqueous was exchanged by air. Thus an air-to-endothelium interface (i.e., a useful optical surface) was created at the posterior corneal surface. The air-to-endothelium interface was used as a reference plane to visualize the corneal thickness and the relative depth of corneal incisions and dissections. Freehand peripheral corneal incisions, tangential keratotomy incisions, and lamellar stromal dissections were made at an intended corneal depth of 60, 80, and 99%. Light microscopy was used to measure the relative depth of the incisions and dissections. RESULTS: Achieved depth for peripheral corneal incisions averaged 65.2+/-5.3%, 78.8+/-5.1%, and 93.4+/-6.0%, respectively (p<0.05); and for tangential keratotomy incisions, 68.2+/-7.3%, 83.2+/-4.4%, and 95.8+/-3.6%, respectively (p<0.05). Achieved depth for lamellar stromal dissections averaged 58.3+/-9.4%, 81.1+/-3.4%, and 94.4+/-1.5%, respectively (p<0.05). Microperforations occurred with three incisions made at 99% intended depth. CONCLUSION: During surgery, the depth of incisions and lamellar dissections relative to the corneal thickness can be visualized by filling the anterior chamber with air (i.e., by creating an optical interface at the posterior corneal surface).     

Psychiatric symptoms in male cannabis users not using other illicit drugs

PURPOSE: To examine the ultrastructure of clear corneal incisions (CCIs) performed with diamond keratomes and steel blades as well as the corneal trauma after implantation of a foldable intraocular lens (IOL) through two incision widths. SETTING: University Eye Clinic and Institute of Histology and Embryology II, University of Vienna, Austria. METHODS: Twenty-four human cadaver eyes without prior ocular surgery were obtained from the University Eye Bank, Vienna. Single-plane CCIs were performed with 3.0 and 3.2 mm Alcon steel blades and with a 3.0 mm Huco diamond keratome. The AMO PhacoFlex II lens was implanted with a Fine II folder. During the entire procedure, the eye pressure was kept between 26 and 30 mm Hg by infusing balanced salt solution into the anterior chamber. Specimens were prepared for light microscopy, transmission electron microscopy, and scanning electron microscopy according to standard procedures. RESULTS: The diamond keratome produced cleaner cuts than the steel blade. After IOL implantation, 3.0 mm steel blade incisions exhibited extensions at their lateral ends. Within these extensions, the collagen lamellae were displaced and torn. This was not true with 3.2 mm tunnels. Because of the thickness of a 3.0 mm diamond keratome, the extent of corneal trauma was between that found with 3.0 and 3.2 mm steel keratome tunnels. CONCLUSIONS: Implantation of the SI-30 through 3.0 mm CCIs produced by the steel blade led to more severe corneal trauma than implantation through 3.2 mm steel blade incisions or 3.0 mm diamond keratome incisions. Thus, IOL implantation through incisions that are too small intensifies corneal trauma.     

Wound healing of scleral self-sealing incision: a comparison of ultrasound biomicroscopy and histology findings

PURPOSE: The goal of this study was to compare the morphologic findings of wound healing in scleral self-sealing incisions using ultrasound biomicroscopy and histology. METHODS: Using a slit-knife, we made a scleral self-sealing incision in the rabbit eye. At various time points postoperatively, ultrasound biomicroscopy was performed to evaluate wound healing; the eyes then were enucleated and studied histologically. We also performed ultrasound biomicroscopy at various time points postoperatively in patients who received a scleral self-sealing incision during cataract surgery. RESULTS: In rabbit eyes, on days 1 and 2 postoperatively, we detected the scleral wound; thereafter, detection became increasingly difficult. On day 7 postoperatively, the wound was undetectable. By light-microscopic observation, the scleral wound was open at 1 day postoperatively. On day 2 postoperatively, fibrovascular tissue barely extended into the wound; on day 5 postoperatively, connective tissue extended through the full thickness of the wound. On day 7 postoperatively, the connective tissue became dense and aligned with the lamella. In human eyes, using ultrasound biomicroscopy, the scleral incision was detectable until 5 days postoperatively, but undetectable at 7 days postoperatively. CONCLUSIONS: Ultrasound biomicroscopy demonstrates the stages of wound healing of scleral self-sealing incisions. We believe that careful observation is necessary for approximately 7 days following self-sealing incision cataract surgery.     

Resource management of cataract patients: effect of four contemporary incisions on postoperative visits required

PURPOSE: To assess the effect of four contemporary cataract surgery incisions on the number of postoperative visits required. SETTING: Cataract service of a large free-standing eye hospital in a capital city. METHODS: This study comprised a prospective evaluation of three incisions for phacoemulsification and a retrospective assessment of age- and sex-matched patients having conventional corneal section extracapsular cataract extraction. All patients had age-related cataract. Main outcome measures were complications, best corrected and uncorrected visual acuities 6 weeks after surgery, and number of visits before discharge. Follow-up was at least 6 months. RESULTS: Patients who had small and scleral incisions had better uncorrected visual acuities 6 weeks postoperatively because they had less astigmatism. Patients who had small and scleral incisions required significantly fewer postoperative visits before discharge. CONCLUSION: A prospective assessment of the feasibility and acceptability of reduced postoperative follow-up after phacoemulsification using a scleral tunnel is required.     

Changes in 31P-relaxation times during organ preservation: observations on cold stored human donor livers

PURPOSE: To compare the clinical outcome of phacoemulsification and foldable silicone intraocular lens (IOL) implantation through a 3.0 mm temporal clear corneal incision and 3.0 mm superior scleral tunnel incision. SETTING: Department of Ophthalmology, Yodogawa Christian Hospital, Osaka, Japan. METHODS: Eighty cataractous eyes of 78 patients with pre-existing against-the-rule (ATR) astigmatism were recruited for this prospective, randomized study. The patients were assigned to one of the two groups. Data on uncorrected and corrected visual acuities, keratometry, flare intensity measurement, and central cornea endothelial cell count were evaluated preoperatively and at 2 days, 1 week, and 1 and 3 months postoperatively. RESULTS: Although the pre-existing keratometric cylinder decreased in the temporal clear corneal incision group and increased in the superior scleral tunnel incision group, the amount of cylinder shift was not significantly different. Mean scalar shift of keratometric cylinder in the corneal incision group was 1.19 diopters (D) at 2 days postoperatively, 0.86 D at 1 week, and 0.56 D at 3 months and in the scleral incision group, 1.09 D at 2 days, 0.76 D at 1 week, and 0.65 D at 3 months. Eighty percent of the eyes in each group achieved an uncorrected visual acuity of 20/40 or better from the second day postoperatively. No statistically significant difference in visual rehabilitation or other parameters was noted between the groups throughout the study. Complications including corneal endothelial cell loss and wound incompetence requiring suturing were observed in the temporal clear corneal incision group. CONCLUSIONS: Both incisions offered satisfactory clinical results, but the superior scleral tunnel incision resulted in fewer complications. Minimal corneal keratometric change induced by a 3.0 mm incision was not related to uncorrected visual rehabilitation.     

Depth of lamellar keratoplasty with the guided trephine system for transplantation of full-thickness donor sections

BACKGROUND: Despite the fact that deep lamellar keratoplasty (DLKP) is less invasive than to penetrating keratoplasty (PKP), this procedure is rarely performed. We therefore investigated whether or not the DLKP technique we employed can achieve stable improvement of visual acuity. MATERIALS AND METHODS: Thirty-three eyes underwent TLKP for treatment of superficial corneal pathology. The donor tissue transplanted was suitable for PKP. The donor lenticule was obtained on the artificial chamber of the guided trephine system (GTS). The recipient cornea was trephined with the same trephine to a depth of 680 microns. Manual dissection was performed with a bevel-up blade. The donor lenticule with the endothelium peeled off was then sutured in with a 10 x 0 nylon double-running antitorque suture. Cortisone-antibiotic eye drops were administered postoperatively. RESULTS: Throughout the series no complications occurred. The mean best corrected visual acuity (BSCVA) over glasses was 0.29 (+/- 0.21) preoperatively, 0.1 (+/- 0.11) at 1 week, 0.33 (+/- 0.14) at 1 month, 0.5 (+/- 0.13) at 6 months, 0.61 (+/- 0.16) at 1 year and 0.63 (+/- 0.15) at 2 years. Clinically, we observed two subpopulations. In the first group of 87% of the cases, mean BSCVA was 0.67 (+/- 0.07) at 6 months. The remaining cases (BSCVA < or = 0.25 at 6 months) achieved a mean BSCVA of only 0.2 (+/- 0.04) at 1 year. Mean corneal astigmatism measured 2.93 D (+/- 1.62) preoperatively, 2.69 D (+/- 1.18) at 1 month, 2.09 D (+/- 1.07) at 1 year, and 2.22 D (+/- 1.11) at 2 years. We did not observe any graft rejection. CONCLUSION: The technique reported for DLKP provides excellent matching of donor lenticule and recipient bed. Separation of donor and recipient stroma prevents interface healing. DLKP appears to be a safe procedure for the surgical treatment of superficial corneal pathology and may offer a clinically applicable alternative to PKP.     

The contribution of A. G. Ginetsinski? to the theory of the chemical transmission of synaptic signals

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.     

Confocal microscopic characterization of wound repair after photorefractive keratectomy

PURPOSE: Development of postoperative corneal haze and regression of refractive effect are unfavorable clinical complications of excimer laser photorefractive keratectomy (PRK). Although exact mechanisms remain to be elucidated, these outcomes have been attributed to post-PRK corneal wound healing. The purpose of this study was to evaluate corneal wound repair quantitatively after PRK in a rabbit model using a newly developed in vivo technique, termed confocal microscopy through focusing (CMTF). METHODS: Twelve rabbit corneas received a monocular, 6-mm diameter, 9.0-diopter PRK myopic correction. Animals were evaluated sequentially up to 6 months after surgery by in vivo CMTF, which uses an image-intensity depth profile to measure epithelial and stromal thickness and uses corneal light reflectivity as an objective estimate of corneal haze. At differing temporal intervals, in vivo morphology was correlated with ex vivo histology using fluorescence microscopy. RESULTS: One week after PRK, an acellular layer of 86 +/- 24 microns was found anteriorly in the remaining stroma, which demonstrated surgically induced keratocyte death. Underlying keratocytes became activated and migrated toward the wound bed; repopulation was completed within 3 weeks. One week after PRK, there was a significant increase (P < 0.001) in light reflections detected from the photoablated stromal surface (1745 +/- 262 U) and from the underlying activated fibroblasts (713 +/- 607 U). Corneal reflectivity peaked at 3 weeks (4648 +/- 1263 U) and decreased linearly to 889 +/- 700 U by 6 months after the PRK; this corresponded to a reflectivity six times greater than the level seen in unoperated corneas. Two weeks after PRK, initial corneal edema had resolved, revealing an actual ablation depth (maximal stromal thinning) of 118 +/- 8 microns. Starting at 2 weeks after surgery, the stroma underwent gradual rethickening that reached 98% of the preoperative thickness at 6 months after PRK; at that time, only 6% of the initial photoablation depth persisted. By contrast, the central corneal epithelium showed no significant postoperative hyperplasia. CONCLUSIONS: Rabbit corneas treated by PRK showed a remarkable stromal wound-healing response that ultimately led to the restoration of the original stromal thickness by 6 months after surgery, demonstrating complete regression of the initial photoablative effect. Additionally, corneal wound healing was associated with increased light reflections from both the photoablated stromal surface and the activated wound-healing keratocytes underlying this area. Based on these findings, the authors hypothesize that the development of clinically observed corneal haze in PRK patients may be related, in part, to activation of corneal keratocytes and to putative changes in the extracellular matrix.