Laser-assisted subepithelial keratectomy (LASEK) without alcohol versus photorefractive keratectomy (PRK)

PURPOSE: To evaluate epithelial healing and visual outcome after laser-assisted subepithelial keratectomy (LASEK) without alcohol de-epithelialization and to compare this technique to photorefractive keratectomy (PRK) in myopia. METHODS: In a series of 1953 patients undergoing bilateral myopic PRK, an epithelial flap could be obtained by manual de-epithelialization in the left eye of 56 patients without alcohol exposure. The right eye was treated by PRK and the left by LASEK (i.e., repositioning the viable flap after surface ablation). The two eyes were compared in terms of pain, uncorrected visual acuity (UCVA) in decimals, correction achieved, and haze. The epithelial healing pattern was assessed in the LASEK eyes. RESULTS: The flap remained viable, showing a peripheral junction, in 25 eyes (45%). Pain was higher in the PRK eye in 11/56 patients (20%), higher in the LASEK eye in 23/56 patients (41%), and the same in both eyes in 22/56 patients (39%). UCVA at one week was slightly better in the LASEK eyes (median 0.7 versus 0.6, p = 0.002 with Wilcoxon test), but was the same in PRK and LASEK eyes after 1 month (median 0.9 in both). Median haze at 6 months was 0.5 in the PRK eyes and 0 in the LASEK eyes (Wilcoxon p = 0.007). Median postoperative defocus equivalent at 9 months was 0.5 diopters in both the PRK and the LASEK eyes. CONCLUSIONS: Although our study might have selected patients with loose epithelium, LASEK performed by manual de-epithelialization in the absence of alcohol exposure is not less painful than PRK, even in case of flap survival. Visual recovery speed, as well as haze, is slightly better than in PRK, although the difference is clinically negligible.     

Epikeratophakia for high myopia.

A cryo-technique for production of corneal epi-lenses has been developed. During the manufacturing procedure the anterior surface of the tissue is moulded and the posterior surface cut with a microtome. After cutting, the epi-lenses are stored for days to weeks in an organ culture medium. Twelve eyes in 10 patients have been treated with epikeratophakia for high myopia (greater than -7 D). In all eyes, epithelialization was complete within one week, and at follow-up 3-18 months after the operation all epi-lenses were clear. The average refractive change in spherical equivalents was 9.7 +/- 4.4 D. All eyes obtained better uncorrected visual acuity, and no eyes lost more than one line of the best corrected visual acuity. At the time of follow-up, the patients' native cornea had regained normal hydration, whereas the epi-lenses did not thin as much as expected.     

Epikeratophakia after ocular trauma

Five patients with long-standing monocular traumatic aphakia and contact lens intolerance underwent epikeratophakia. This procedure was chosen to rehabilitate the visual function in those eyes that exhibited distorted anterior segment anatomy after trauma. Three of the patients had corneal scars associated with their old perforation wounds, and all of them had undergone an intracapsular cataract extraction soon after their original injuries. Best-corrected visual acuity was 20/50 or better in all cases before surgery. Postoperative best-corrected visual acuity improved to within two lines of the best-corrected preoperative visual acuity, after a minimum follow-up period of six months. No intraoperative complications were noted. One cornea developed late-onset partial scarring of the interface in the area of the original scar, but the process arrested spontaneously.     

Epikeratophakia for Myopia Correction

Epikeratophakia is based on the principles of the Barraquer refractive procedures, with modifications that simplify the surgical technique and eliminate the use of the microkeratome by placing the donor corneal tissue lens on the anterior surface of the cornea. Procedures developed to permit freeze-drying the preshaped lens for storage enable these lenses to be obtained from a central source, freeing the surgeon from the complexities of the computer and the cryolathe. The correction of theoretically unlimited amounts of myopia is possible with these lenses. In 12 eyes that underwent the final epikeratophakia procedure, the average desired correction achieved was 98%.     

Photorefractive keratectomy with and without smoothing: a bilateral study

PURPOSE: To assess whether a smoother stromal surface and a faster epithelium regeneration after excimer laser photorefractive keratectomy (PRK) may lead to better visual results. METHODS: Ten patients had unilateral PRK and contralateral PRK plus smoothing. The operative outcome was checked by means of digital standardized photographs taken at 0, 20, 40, and 60 hours after surgery. Complete clinical examinations were performed before and 1 and 3 months after surgery. RESULTS: Between 20 and 40 hours after surgery, the average velocity of radial epithelial migration in eyes in which smoothing was performed was 0.083 +/- 0.008 mm/h. This was faster than that (0.064 +/- 0.007 mm/h [P<.01]) observed in the eyes without smoothing. The corneal regularity index at 1 and 3 months was worse in the PRK alone group compared to the PRK plus smoothing group (P=.1). At 3 months, better visual outcome and less haze were observed in the PRK plus smoothing group. CONCLUSION: When using a flying spot laser, PRK plus smoothing improved the visual results and diminished regression and haze at 3 months, but gave rise to a slight hyperopic shift.     

Epikeratophakia for control of pediatric bullous keratopathy

A child who had had a congenital cataract phacoemulsified at age four months became contact lens intolerant, and at age two years had an implantation of a Worst metal-looped iris-clip intraocular lens. He developed painful pseudophakic bullous keratopathy three years later. Since the child remained with dense deprivation amblyopia and contact lens intolerance, when the IOL was removed an epikeratophakia graft was applied. The bullous keratopathy resolved and the patient has remained asymptomatic for 22 postoperative months. The proposed mechanism for relief of the bullous keratopathy is to increase tissue thickness and resistance, thus reducing fluid volume transferred to the subepithelial space.     

异种表层角膜镜术的实验研究

在猴-猴表层板层角膜移植术成功的基础上,进行了三例人-猴异种表层角膜镜片术。术眼均获透明愈合。观察期分別为1个月、3个月和2年。对3例表层角膜镜片术的术眼角膜进行了组织学检查,发现上皮厚度及基质角膜细胞正常,进行异种表层角膜镜片术必须根据以下三个因素:供受体组织结构和屈光参数相近;供体角膜要有前弹力膜和一定的厚度。另外,对手术方法也进行了某些改进。     

表层角膜镜片术治疗圆锥角膜

采用表层角膜镜片术联合前房穿刺，手术治疗18例21眼圆锥角膜患者，经术后3个月～1年8个月的随访，患者的视力、矫正视力明显提高，角膜屈光力显著降低，平均为45．83D。认为对确诊为圆锥角膜但尚无后弹力层破裂，或中央视区尚未形成瘢痕的患者，应早期行该术治疗，术后疗效确切，作用持久，稳定。     

Epikeratophakia for the treatment of hyperopia

Nordan epikeratophakia technique (NET) is described for the treatment of hyperopia and the results in eight eyes are reported (mean = +5.09 +/- 0.85 diopters preoperatively and -2.09 +/- 1.22 diopters postoperatively). The Nordan epikeratophakia technique is a modification of Kaufman-McDonald epikeratophakia with advantages that are described. Data are analyzed according to traditional means in addition to newer indices that consider both the uncorrected visual acuity and the refractive error.     

Epikeratophakia: histopathological and cultural study

Summary Three epikeratoplasty buttons (one aphakic and two myopic) prepared by the freeze technique were removed two to nineteen months after surgery. A complete morphological and immunohistochemical study was performed on these buttons in order to gain insight into the reasons for epikeratophakia failure. Histopathological studies with light microscopy and scanning and transmission electron microscopy were performed. All three cases showed an anomalous process of re-epithelialization: in the first, the epithelium over the donor cap was almost completely absent, with many abnormalities; in the second, the epithelium was irregular, with a varying number of cell layers and poor adhesion between cells; in the third, the development of an epithelial cyst between the tissue lens and the cornea of the host caused the failure of the epikeratoplasty.The specimens were cultured in vitro and the cells grown typed for HLA antigens. The antigen panel was the same as that of the host. Immunohistochemistry showed CD3- and CD8-positive cells in the stroma, proving the activity of T-suppressor lymphocytes in a cell-mediated immunoreaction.     

用角膜接触镜制造车床切削表面角膜镜

介绍了英国具有半径旋转功能的ＰＡＬｕｎｉｖｒｓａｌ型角膜接触镜精密车床所设计的冷冻装置。此装置基部与车床夹头相匹配，冻盘直径０．９ｍｍ，凹面曲率８ｍｍ，以液氮气体为制冷源，将供体角膜冻贴于装置上进行切削。包括供体角膜的预备和应用公式的选择，以及车床切削半径的确定以制作表面角膜镜片。     

表面角膜镜片术用于美容的初步报告

将表面角膜镜片手术用于临床进行美容，治疗7例7眼获得满意效果。此方法具有不易脱色，组织损伤轻，手术可逆等特点，是一种有效的手术方法。优于以往的角膜染色术。     

Epikeratophakia following rotational autokeratoplasty in a child

A 3-year-old child with posttraumatic aphakia and a corneal scar was treated with a rotational penetrating ipsilateral autokeratoplasty followed by epikeratophakia 2 months later. His final best corrected visual acuity was 20/30, with 1.37D of corneal astigmatism. There were no significant operative or postoperative complications.     

室温下切削表面角膜镜片的实验研究

报道了表面角膜镜的制作技术。用无形眼镜车床、聚乙烯吡咯烷酮粘合剂，将干燥成形的角膜粘合于ＰＭＭＡ凹模，在室温下切削角膜片。１２只新西兰兔行表面角膜镜术，术后６只获得透明愈合，平均观察８０．８３天（７５－９２天）。角膜屈光度平均较术前增加９．４５Ｄ（８．９０－１１．２６Ｄ）。并报道了兔表面角膜镜术后的病理修复过程。结果显示该方法制作表面镜简便、有效。