Isabelle Brunette

Functional outcome and satisfaction after photorefractive keratectomy: Part 2: survey of 690 patients

PURPOSE To document patient satisfaction and self-perceived quality of vision after bilateral photorefractive keratectomy (PRK). DESIGN Noncomparative, interventional case series. PARTICIPANTS Consecutive patients who underwent bilateral PRK from May 1994 through May 1997 by the 12 surgeons of four collaborating centers with a minimum of 4 months since the last surgery and up to 30 months since the first surgery. METHODS A questionnaire with known psychometric properties was self-administered by the patients. MAIN OUTCOME MEASURES Responses to individual questions and scale scores. RESULTS A total of 929 questionnaires were sent, of which 690 were answered and returned (74.3% response rate). The preoperative spherical equivalent ranged from -0.38 diopters [D] to -27.75 D (mean, -5.32 D; standard deviation, 2.85 D). Although 91.8% of the patients were satisfied or very satisfied with their surgery, 96.3% considered that their main goal had been reached, and 95.7% would still choose to have surgery if they had it to do over. The degree of satisfaction was proportional to the postoperative uncorrected visual acuity in the best eye expressed in LogMAR (r = -0.18, P: = 0. 0001) and was negatively correlated with the importance of the corneal haze (r = -0.23, P = 0.0001). Daytime glare was reported to be greater than before surgery by 55.1% of patients. A decrease in night vision was reported by 31.7% of patients, and 31.1% of patients reported increased difficulty driving at night because of their vision. CONCLUSIONS Overall satisfaction after PRK for low to severe myopia appears to be very good. Glare and night vision disturbance, particularly bothersome for night driving, seem to constitute significant secondary effects that deserve further investigation and should be kept in mind for future improvements in the technique.

Amniotic membrane transplantation and fibrin glue in the management of corneal ulcers and perforations: a review of 33 cases.

Purpose: To evaluate the efficacy of amniotic membrane in corneal ulcers refractive to conventional treatment and amniotic membrane with fibrin glue in corneal perforations. Methods: Amniotic membrane transplantation (AMT) was performed in 33 eyes from 32 patients for corneal ulcers refractive to conventional treatment. Fourteen ulcers were perforated and received fibrin glue and amniotic membrane. Ulcers were divided into 3 groups: neurotrophic or exposure, autoimmune, and other etiology. Results: Overall success was observed in 80% (27/33 eyes) of the cases, with success rates of 87.5% (14/16 eyes), 70% (7/10 eyes), 85.7% (6/7 eyes) in groups 1, 2, and 3, respectively. The ulcers healed in a mean time of 3.6 ± 1.6 weeks and the follow-up was 14.8 ± 9.9 months. Failure was noted in 6 eyes with severe neurotrophic keratitis, Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and Acanthamoeba keratitis. Grafts with fibrin sealant showed a success rate of 92.9 % (13/14 eyes) compared to 73.7% (14/19 eyes) for amniotic grafts alone. In patients with severe limbal damage, a success rate of only 20% (1/5) was observed. Conclusions: AMT is a viable option in the treatment of nonhealing corneal ulcers of various depth and etiologies. Perforations up to 3 mm can be safely managed by fibrin glue and AMT. These techniques lead to rapid reconstruction of the corneal surface and can give a good final functional result or allow keratoplasty to be done in more favorable conditions.

Stable corneal regeneration four years after implantation of a cell-free recombinant human collagen scaffold.

We developed cell-free implants, comprising carbodiimide crosslinked recombinant human collagen (RHC), to enable corneal regeneration by endogenous cell recruitment, to address the worldwide shortage of donor corneas. Patients were grafted with RHC implants. Over four years, the regenerated neo-corneas were stably integrated without rejection, without the long immunosuppression regime needed by donor cornea patients. There was no recruitment of inflammatory dendritic cells into the implant area, whereas, even with immunosuppression, donor cornea recipients showed dendritic cell migration into the central cornea and a rejection episode was observed. Regeneration as evidenced by continued nerve and stromal cell repopulation occurred over the four years to approximate the micro-architecture of healthy corneas. Histopathology of a regenerated, clear cornea from a regrafted patient showed normal corneal architecture. Donor human cornea grafted eyes had abnormally tortuous nerves and stromal cell death was found. Implanted patients had a 4-year average corrected visual acuity of 20/54 and gained more than 5 Snellen lines of vision on an eye chart. The visual acuity can be improved with more robust materials for better shape retention. Nevertheless, these RHC implants can achieve stable regeneration and therefore, represent a potentially safe alternative to donor organ transplantation.

Corneal endothelial cell density in glaucoma.

Purpose We studied corneal endothelial cell density in patients with glaucoma. Methods One hundred two patients with glaucoma were compared with 52 patients without glaucoma of the same age group. Exclusion criteria included history of either corneal disease, ocular inflammation, trauma, or surgery other than peripheral iridectomy. The following data were extracted from the patient files: glaucoma type and duration, laser treatments, glaucoma medications, and documented intraocular pressure (IOP) measurements. Specular microscopies were performed on central corneas, endothelial images were analyzed by computerized planimetry, and cell counts were calculated. Results Corneal endothelial cell counts were significantly lower in patients with glaucoma (2,154 ± 419 cells/mm2) than in controls (2,560 ± 306 cells/mm2; t test, p < 0.0001). In the glaucoma group, cell counts were inversely proportional to the means of IOPs. Patients receiving three or four glaucoma medications had lower cell counts than those receiving one or two medications. Cell counts were significantly lower both in primary angle-closure glaucoma and in primary open-angle glaucoma. Conclusion This study suggests that patients with glaucoma may have lower corneal endothelial cell density than those without glaucoma of the same age group. The proposed mechanisms are direct damage from IOP, congenital alteration of the corneal endothelium in patients with glaucoma, glaucoma medication toxicity, or a combination of these.

Functional outcome and satisfaction after photorefractive keratectomy. Part 1: development and validation of a survey questionnaire.

OBJECTIVE The aim of this study was to develop a valid, reliable, and easy-to-administer instrument to assess patient satisfaction and perceived outcome after bilateral excimer laser photorefractive keratectomy. DESIGN Development and validation of a psychometric questionnaire. PARTICIPANTS Consecutive patients who underwent bilateral excimer laser photorefractive keratectomy from May 1994 through May 1997 by 12 surgeons from four collaborating centers. To be eligible, a minimum of 4 months since the last surgery and a maximum of 30 months since the first surgery was required. METHODS The new instrument was derived in part from the Prospective Evaluation of Radial Keratotomy (PERK) study 10-year psychometric questionnaire and the Visual Functional Index (VF-14), an index of functional impairment in patients with cataract. Questions were grouped in seven scales, each covering a specific aspect of quality of vision. These included global satisfaction, quality of uncorrected vision, quality of corrected vision, quality of night vision, glare, daytime driving, and night driving. MAIN OUTCOME MEASURES Acceptability, reliability, validity, and interpretability of the instrument, as well as its ease of administration. RESULTS The instrument scale structure was examined and scale scores were created. Item-discriminant validity ensured that questions belonged to their hypothesized scale, based on multitrait correlation analysis. The instrument was shown to be reliable by a high level of internal consistency, and all Cronbachs alpha coefficients were superior or equal to 0.83. Construct-related validity and interpretability were assessed based on correlations between scale scores and clinically recognized success criteria such as visual acuity and refraction. Respondent burden was shown to be minimal. Acceptability of the instrument was shown to be very good, with a participation rate of 74.3% (690 of 929 patients). The instrument is available in English and in French and the translation was shown to be reliable. CONCLUSIONS The acceptability, reliability, and interpretability of the instrument, as well as its ease of administration, were shown to be adequate. This questionnaire appears clinically useful to document patient satisfaction after excimer laser photorefractive keratectomy.

Average 3-Dimensional Models for the Comparison of Orbscan II and Pentacam Pachymetry Maps in Normal Corneas

PURPOSE To assess the reliability of Orbscan (Bausch & Lomb, Salt Lake City, UT) and Pentacam (Oculus, Wetzlar, Germany) central corneal thickness (CCT) and peripheral corneal thickness (PCT) measurements based on 2 methodologies. DESIGN Evaluation of a diagnostic technology. PARTICIPANTS Thirty healthy volunteers were recruited prospectively at the Department of Ophthalmology of the Hôtel-Dieu Hospital, Paris, France. METHODS Central corneal thickness and PCT were assessed, using ultrasound pachymetry (USP) as the gold standard. Two methodologies were used: (1) the traditional analysis of pachymetry data from 1 central and 8 peripheral reference positions on the cornea, and (2) a 3-dimensional (3-D) analysis based on average corneal pachymetry maps constructed for each system (Orbscan, Pentacam, and USP), each operator (operators 1 and 2), and each visit (visits A and B). MAIN OUTCOME MEASURES Repeatability, intersystem reproducibility, interoperator reproducibility, reproducibility over time, and accuracy of Orbscan and Pentacam CCT and PCT measurements. Distribution and statistical significance of the differences between 3-D average maps. RESULTS Repeatability (Orbscan intraclass correlation coefficients [ICCs], 0.967-0.992; Pentacam ICCs, 0.986-0.997), interoperator reproducibility, and reproducibility over time (ICCs, 0.976-0.997) were excellent to almost perfect for both systems. Intersystem agreement was almost perfect for CCT (ICC, 0.980), but less strong for PCT (ICCs, 0.928-0.979). Despite a good to excellent agreement between the optical systems and USP (ICCs, 0.608-0.958), USP CCT readings were thicker (mean difference, up to 15.2 microm; P<0.05), and USP PCT readings were thinner (P<0.05). Orbscan and Pentacam average maps allowed comprehensive interpretation of differences between populations according to the magnitude, distribution, and statistical significance, minimizing the risk of giving excessive weight to few data measured at specific locations on the cornea. CONCLUSIONS Both methodologies showed that Orbscan and Pentacam CCT readings are interchangeable, whereas caution should be used for PCT readings. Interchangeability with USP measurements also was shown to be limited. The high repeatability, interoperator reproducibility, reproducibility over time, the extent of the information generated by a single capture, and the noncontact nature of the Orbscan and Pentacam all suggest that optical systems eventually may replace USP as the gold standard for corneal pachymetry.

The VF-14 index of functional visual impairment in candidates for a corneal graft ☆

PURPOSE To validate the Visual Function-14 (VF-14) index of functional visual impairment in candidates for a corneal graft. METHODS One hundred thirty-four patients who were candidates for a corneal graft participated in this study between August 1996 and February 1997. Demographic, ocular history, best-corrected visual acuity, and detailed ocular examination data were collected. Functional visual impairment information was obtained by telephone interviews using the following: VF-14, SF-36 (Short Form-36, a more generic measure of general health function), and Visual Symptom Score, and four questions measuring the overall amount of trouble with vision, dissatisfaction with vision, ocular pain, and discomfort. RESULTS The average age of corneal graft candidates was 64 +/- 18 years (range, 18 to 90 years) and 60% were women. The most frequent corneal disease was pseudophakic bullous keratopathy (41%). Ocular comorbidities included glaucoma or ocular hypertension (30%) and cataract (19%). The mean best-corrected visual acuity of the eye scheduled for surgery was 1.33 +/- 0.56 logMAR whereas the best eye best-corrected visual acuity was 0.36 +/- 0.44 logMAR. The mean VF-14 score was 73% +/- 26%, and the internal consistency was high, with a Cronbach alpha value of 0.94. The VF-14 correlated strongly with the best eye best-corrected visual acuity. It also correlated strongly with the Visual Symptom Score, the global measures of trouble and dissatisfaction with vision. Candidates for a corneal graft had low scores for all eight general health concepts evaluated with the SF-36, and the VF-14 correlated with seven of the eight SF-36 subscales. CONCLUSION The VF-14 is a valid measure of functional visual impairment in candidates for a corneal graft. The Visual Symptom Score and the SF-36 are also useful indices in such patients.

Laser ablation threshold dependence on pulse duration for fused silica and corneal tissues : experiments and modeling

The surface ablation threshold fluence of fused silica and two porcine cornea layers, the epithelium and the stroma, is characterized as a function of the laser pulse duration in the range of 100 fs-5 ps for a wavelength of 800 nm (Ti:sapphire laser system). The plateaulike region observed between 100 fs and 1 ps for the corneal layers indicates that for use in laser surgery, laser pulse durations chosen within this range should be practically equivalent. Our model predicts that the ablation threshold will decrease rapidly for pulse durations in the low end of the femtosecond regime.

Tissue engineering of feline corneal endothelium using a devitalized human cornea as carrier.

The difficulties in obtaining good quality tissue for the replacement of corneas of patients suffering from endothelial dysfunctions have prompted us to evaluate the feasibility of producing a tissue-engineered (TE) corneal endothelium using devitalized human stromal carriers. Thus, corneal substitutes were produced by seeding cultured feline corneal endothelial cells on top of previously frozen human corneal stromas. After two weeks of culture to allow attachment and spreading of the seeded cells, the TE corneal endothelium was stained with alizarin red for endothelial cell count and fixed for histology, immunofluorescence labeling, scanning and transmission electron microscopy. Histology and Hoechst staining showed that there were no remaining cells in the devitalized stroma. After seeding, histology and transmission electron microscopy showed that the TE corneal endothelium formed a monolayer of tightly packed cells that were well adhered to Descemets membrane. Scanning electron microscopy corroborated that the cells covered the entire posterior corneal surface and had an endothelial morphology. Alizarin staining showed that mean cell counts were 2272 +/- 344 cells/mm(2), indicating that the cell density was appropriate for grafting. The TE feline corneal endothelium also expressed the function-related proteins Na(+)/HCO(3)(-), ZO-1, and Na(+)/K(+)-ATPase alpha1, and could easily be marked with a fluorescent tracker. This study demonstrates the feasibility of reconstructing a highly cellular and healthy corneal endothelium on devitalized human corneal stromas.

Corneal Transplant Tolerance of Cryopreservation

Purpose. To study the outcome of corneal transplants performed with cryopreserved tissue. Methods. Maisonneuve-Rosemont Hospital medical records of all corneal transplantations performed with cryopreserved tissue by one surgeon (M.L.F.) between March 1978 and April 1991 were reviewed. The Kaufman–Capella cryopreservation technique was used. Corneas were cryopreserved for periods of 3 days to 16.8 years (mean, 4.6 years) before transplantation. Results. We report a mean follow-up of 54 months (range, 2.8–151.3 months). Survival analysis showed the probability of a clear graft to be 76% at 1 year and 73.2% at 2 years. At the time of the last visit, visual acuity was 20/40 or better in 61 eyes (49.2%). The mean postoperative pachometry was 0.58 mm (range, 0.50–0.75 mm). Specular microscopy performed in 57 eyes showed a mean endothelial cell count of 938 cells/mm 2 55.1 months (range, 2.9–151.3 months) after surgery. For comparison purposes, the outcome of a subgroup of cryopreserved (n = 33) and noncryopreserved (n = 26) corneas transplanted by the same surgeon between April 1986 and April 1990 was studied. Conclusion. Despite an increase in the primary failure rate and higher initial endothelial cell loss, cryopreserved transplants are viable. Although we do not recommend cryopreservation of corneas for elective surgery, we consider that cryopreserved corneas can be very useful in emergency situations when tissue availability is a problem.