Phototherapeutic Keratectomy For Treatment Research Articles

Safety and Efficacy of the Phototherapeutic Keratectomy for Treatment of Recurrent Corneal Erosions: A Systematic Review and Meta-Analysis

Background: Phototherapeutic keratectomy (PTK) has been increasingly used to treat severe recurrent corneal erosion syndrome (RCES) patients who do not respond to other treatments. However, the efficacy and complication of each study are currently uncertain due to varying rates. Objectives: The objective of this study was to investigate the safety and efficacy of the PTK for recurrent corneal erosions. Methods: This article performed a systematic literature research in Cochrane, Embase, PubMed, Scopus, and the Web of Science for the literature on PTK treatment of RCES until December 20, 2022. The extracted data including recurrence rate and the adverse event rate were used for meta-analysis. Results: The recurrence rate was 18% (95% CI, 13%–24%) (129/700 eyes). Subgroup analysis showed that the RCE recurrence was 17% (95% CI, 9%–24%) after trauma and 22% (95% CI, 11%–32%) in the corneal dystrophy group. Treatment-related adverse events included subepithelial haze, hyperopic shift, and decrease of the best spectacle-corrected visual acuity. In this study, the incidence of these events was 13% (95% CI, 6%–21%), 20% (95% CI, 11%–28%), and 11% (95% CI, 5%–16%), respectively. Conclusions: PTK represented a valuable treatment option for patients with recurrent corneal erosions, especially those with traumatic injuries, which had minimal side effects.

Large Population Outcomes of Small Incision Lenticule Extraction in Young Myopic Patients.

To evaluate the outcomes of small incision lenticule extraction (SMILE) for myopia in a large population of young adults. In this retrospective case series, the patient population consisted of the first 4,138 consecutive SMILE treatments using the VisuMax femtosecond laser (Carl Zeiss Meditec) between 2012 and 2018 at the London Vision Clinic. Inclusion criteria were myopic spherical equivalent up to -9.00 diopters (D), cylinder up to 6.00 D, corrected distance visual acuity of 20/20 or better, age younger than 40 years, and follow-up of 12 months. Outcomes analysis was performed using the Standard Graphs for Reporting Refractive Surgery. Data were available at 12 months in 3,722 eyes (90%), and 416 eyes (10%) were lost to follow-up. Mean attempted spherical equivalent refraction (SEQ) was -4.61 ± 1.84 D (range: -1.12 to -9.00 D). Mean cylinder was -0.78 ± 0.66 D (range: 0.00 to -6.00 D). Postoperatively, the mean SEQ relative to target was -0.13 ± 0.30 D (range: -1.35 to +1.25 D) and was within ±0.50 D in 88.1% and ±1.00 D in 99.6% of eyes. Uncorrected distance visual acuity was 20/20 or better in 95.4% of eyes and 20/25 or better in 98.7% of eyes. One line of CDVA was lost in 3.0% of eyes, and 0.08% (n = 3) lost two or more lines of CDVA, for which CDVA was restored following phototherapeutic keratectomy treatment. There was a statistically significant improvement of 0.05, 0.06, 0.07, and 0.07 log units for contrast sensitivity at 3, 6, 12, and 18 cycles per degree, respectively (P < .001). SMILE achieved excellent outcomes for myopia up to -9.00 D with cylinder up to -5.50 D for a large population in patients without presbyopia. [J Refract Surg. 2022;38(8):488-496.].

Phototherapeutische Keratektomie bei rezidivierenden Hornhauterosionen verschiedener epithelialer Genese: Einfluss der Ablationstiefe auf Pachymetrie und Refraktion

Phototherapeutic keratectomy (PTK) is an established treatment method for patients suffering from either genetic corneal dystrophy or recurrent corneal erosion (RCE) without underlying basement membrane dystrophy, often caused by trauma. This study aimed to describe the changes in manifest subjective refraction and pachymetry after PTK treatment in patients suffering from epithelial basement membrane dystrophy (EBMD) and traumatic or atraumatic RCE without underlying EBMD. This was aretrospective, single-center study performed at the Department of Ophthalmology of the Ludwig-Maximilians University (Munich). Patient data were retrospective collected using the smart-eye database of the Department of Ophthalmology including diagnostic data from an autorefractometer and from the Pentacam HR. All laser treatments were performed with an ablation depth of 10 μm for EBMD patients and 6 μm for RCE patients without EBMD. Both collectives showed adecrease in pachymetry larger than the calculated ablation depths after afollow-up interval of 126days (95% CI 104-147days). While the EBMD collective receiving an ablation of 10 μm showed adecrease of 25.8 μm (N = 74; 95% CI 21.2-30.3; p < 0.001), the non-EBMD collective receiving an ablation of 6 μm showed a decrease of 12.3 μm (N = 44, 95% CI 7.0-17.7; p < 0.001). Both, total corneal refractive power (TCRP) as well as spherical equivalent (SE) offered no significant change in preoperative and postoperative comparison for the EBMD collective. On the other hand, patients without underlying EBMD showed asignificant myopic decrease in SE of 0.4 dpt (±0.7 dpt SD, p < 0.05). The mean follow-up interval was 126 days (95% CI 104-147 days). PTK treatment offers an effective method for patients suffering from either EBMD dystrophy or RCE syndrome without underlying EBMD. The final ablation based on pachymetry at the apex can be estimated at 2.3 to 2.6 times higher compared to the original ablation depth. The reasons for this are on the one hand the laser ablation itself and the influence of the reactive wound healing of the corneal epithelium.

P-13 Trans-epithelial phototherapeutic keratectomy (PTK) for recurrent corneal erosion syndrome (RCES).

All patients who received PTK treatment for RCES had failed more than one conventional treatment, and were first vetted and approved by the British Columbia public health authority. A retrospective chart review and telephone survey were conducted at the Pacific Laser Eye Centre. Exclusion criteria were ocular co-morbidities potentially affecting treatment efficacy. This study included 593 eyes of 555 patients (46.2% male; 50.9±14.2 years old) who underwent PTK. The leading identified causes of RCES were trauma (45.7%) and anterior basement membrane dystrophy (44.2%). The most common pre-PTK interventions were ocular lubricants (90.9%), hypertonic solutions (77.9%), and bandage contact lenses (50.9%). 36 eyes had undergone surgical interventions such as stromal puncture, epithelial debridement, or diamond burr polishing. Post-PTK, 78% of patients did not require any subsequent therapies, 20% required ongoing drops and 6 patients (1.1%) reported no symptom improvement. All 6 eyes were successfully retreated with PTK between 11.3±14.9 months from initial PTK. All study patients showed no significant differences in best corrected visual acuity pre vs. postoperatively. When compared to other surgical options, PTK is potentially more costly but frequently more effective and has a high safety profile. The third-party public health vetted nature of this study, the high patient satisfaction, and the low recurrence rate of RCES suggest that PTK should be considered at an earlier stage in the management of RCES.

Clinical outcomes of simultaneous phototherapeutic keratectomy and photoastigmatic keratectomy

This study was aimed to assess the outcomes of simultaneous phototherapeutic keratectomy (PTK) and photoastigmatic keratectomy (PAK), with special attention to astigmatic correction. We comprised 70 eyes of 70 patients who underwent simultaneous PTK and PAK in patients having granular corneal dystrophy and band keratopathy with refractive astigmatism of 1 diopter (D) or more. Preoperatively and 6 months postoperatively, we assessed corrected uncorrected distance visual acuity (UDVA), distance visual acuity (CDVA), manifest spherical equivalent, refractive astigmatism, corneal astigmatism, and higher-order aberrations (HOAs). LogMAR CDVA significantly improved, from 0.27 ± 0.27 preoperatively, to 0.13 ± 0.21 postoperatively (Paired t test, p < 0.001). LogMAR UDVA also significantly improved, from 0.70 ± 0.32 preoperatively, to 0.57 ± 0.41 postoperatively (p = 0.043). Refractive astigmatism significantly decreased, from 2.12 ± 0.95 D preoperatively, to 0.89 ± 0.81 D postoperatively (p < 0.001). Corneal astigmatism also significantly decreased, from 2.17 ± 0.90 D preoperatively, to 1.08 ± 0.71 D postoperatively (p < 0.001). Corneal HOAs did not significantly change, from 0.54 ± 0.30 µm preoperatively, to 0.48 ± 0.20 µm postoperatively (p = 0.140). No significant complications occurred in any eye. Simultaneous PTK and PAK treatment is effective not only for improving visual acuity, but also for reducing astigmatism.

Management of progressive keratoconus with partial topography-guided PRK combined with refractive, customized CXL - a novel technique: the enhanced Athens protocol.

PurposeTo report a novel application of partial topography-guided photorefractive keratectomy combined with topographically customized, higher fluence, and variable pattern corneal cross-linking applied on the same day of the treatment of keratoconus.MethodsA topography-guided partial photorefractive keratectomy treatment of maximum 30 µm over the thinnest cone area was applied initially followed by a 7 mm, 50 µm phototherapeutic keratectomy treatment to address epithelial removal. 0.02% Mitomycin C was applied for 20 seconds and then the exposed stroma was soaked with 0.1% riboflavin solution for 5 minutes. The cornea was then treated with a customized, variable-pattern and 20 mW/cm2 fluence for a total of 5–10 J, and up to 15 J of energy was delivered with the KXL-II device employing an active tracker. The center of the pattern that received the 15 J was topography-matched with the thinnest area of the cone. Visual acuity, refractive error, cornea clarity, keratometry, topography, pachymetry with a multitude of modalities and endothelial cell density were evaluated over 36 months.ResultsKeratoconus was stabilized in all cases. The severity of keratoconus stage by Amsler– Krumeich criteria improved from an average of 3.2 (1–4) to 1.8 (0–3). Uncorrected distance visual acuity changed from preoperative 20/80 to 20/25 at 6 months. A maximum astigmatic reduction of 7.8 D (5.3–15.6), and a significant cornea surface normalization (an index of height decentration improvement from 0.155 [±0.065] to 0.045 [±0.042]) were achieved by 1 month and remained relatively stable for 36 months postoperatively. Two cases delayed full reepithelialization for up to 9 days.ConclusionThis paper introduces a novel technique in order to maximize the refractive normalization effect along with ectasia stabilization in young keratoconus patients. This may facilitate the use of less tissue ablation, in comparison to utilizing a homogeneous UV light beam for corneal cross-linking in Athens Protocol cases. It broadens the number of potential candidate cases that would have been limited to employ this technique due to tissue thickness limitations.

Optical Coherence Tomography-Guided Transepithelial Phototherapeutic Keratectomy for Central Corneal Opacity in the Pediatric Population.

Purpose To report the outcomes of optical coherence tomography- (OCT-) guided transepithelial phototherapeutic keratectomy (PTK) for central corneal opacity in the pediatric population. Methods The charts of 10 eyes of 8 children aged 9 to 17 with central corneal opacity from various pathologies who underwent a standardized OCT-guided transepithelial PTK technique at a single private practice institution were retrospectively reviewed. The corneal topographic findings, OCT measurements, and visual results with refractive outcomes were analyzed 6 months after the PTK treatment. Results All 10 eyes tolerated the procedure well without any significant intraoperative or postoperative complications. Uncorrected and best spectacle-corrected visual acuity (BSCVA) significantly improved postoperatively (p < 0.0001 and p=0.0045, respectively). The absolute value of spherical equivalent on cycloplegic refraction significantly improved postoperatively as well (p=0.0014), but there were no significant changes in topographic measurements. Seven out of the 10 eyes had complete resolution of the central corneal opacity on OCT imaging. None of the subjects lost any lines of BSCVA and developed recurrence of the corneal opacity from the primary disease condition or required keratoplasty during the follow-up period. Conclusions OCT-guided transepithelial PTK can provide excellent visual outcomes in pediatric patients with central corneal opacities.

Phototherapeutic Keratectomy: Science and Art.

To describe, with videos, the principles of excimer laser phototherapeutic keratectomy (PTK) for the treatment of corneal scars, corneal surface irregularity, and recurrent corneal erosions. Depending on the pathology in a treated cornea, the epithelium is removed either by transepithelial PTK ablation with the excimer laser or thorough scraping with a scalpel blade. Stromal PTK can be performed with or without photorefractive keratectomy (PRK), depending on the refractive status of both eyes. Residual surface irregularity is treated with masking-smoothing PTK. Typically, 0.02% mitomycin C treatment is applied for 30 seconds to corneas treated with PTK for scars and surface irregularity. Transepithelial PTK with masking-smoothing typically improves corrected distance visual acuity in the eye even if the entire stromal opacity cannot be removed and can be used to debulk surface irregularity to facilitate subsequent therapeutic customized wavefront-guided or optical coherence tomography-guided PTK or PRK. PTK for recurrent erosion is performed after thorough mechanical epithelial debridement of redundant epithelial basement membrane (EBM) with a scalpel and should only include a dusting of excimer laser to remove residual EBM without inducing central irregular astigmatism or damaging limbal tissues. Meta-analyses are provided for PTK treatment for corneal scars, corneal dystrophies, and recurrent corneal erosions. Excimer laser PTK is a highly effective treatment for superficial corneal scars, central corneal irregular astigmatism, and recurrent corneal erosions unresponsive to medical treatment or mechanical epithelial debridement alone. [J Refract Surg. 2017;33(3):203-210.].

Phototherapeutic Keratectomy for Treatment of Corneal Diseases : Our Experience at King Hussein Medical Center

phototherapeutic keratectomy for various corneal conditions were included in the study. Patients with any systemic disease that would affect epithelial healing such as diabetes or systemic lupus were excluded from the study. Data was collected including patient's age, gender, visual acuity, primary diagnosis, refraction, corneal thickness using Pentacam (Oculus, Wetzlar, Germany) and presence of any systemic disease. All patients were followed after one week of treatment. Bandage contact lens was removed and the cornea checked for epithelial healing and the patients were followed up for at least 6 months after treatment. Results: One hundred and forty-six eyes of 146 patients with a mean age of 57 years (range 7 to 74 years) were enrolled in the study, 87 of them were males. The most common type of corneal pathology found was band keratopathy (37%) followed by old superficial corneal scars (22%), other pathologies found included: Salzmann nodules (12%), bullous keratopathy (9%), spheroidal degeneration (6%), keratoconus with nebula (6%), granular dystrophy (3%), Reis Buckler dystrophy (3%) and recurrent corneal erosions syndrome (3%). Ninety percent of patients experienced improvement in their vision. All patients showed satisfactory improvement in either visual acuity or symptoms of pain and discomfort in the immediate post operative period. Conclusion: Phototherapeutic keratectomy is a safe and very effective procedure to be used for treatment of various surface corneal lesions.

Pathologically Reduced Subbasal Nerve Density in Epithelial Basement Membrane Dystrophy Is Unaltered by Phototherapeutic Keratectomy Treatment

To investigate the effect of phototherapeutic keratectomy (PTK) treatment on corneal epithelial wing cell and corneal subbasal nerve density in epithelial basement membrane dystrophy (EBMD). A total of 39 patients with EBMD who underwent PTK treatment, 40 healthy volunteers, and 24 untreated eyes with EBMD were examined with laser-scanning in vivo confocal microscopy (IVCM). Corneal subbasal nerves and epithelial wing cells were manually quantified from IVCM images by two observers, while epithelial wing cells were additionally quantified by a fully automated method. Subbasal nerve density was significantly reduced in untreated (10,164 ± 4139 μm/mm(2); n = 24) and PTK-treated (10,624 ± 4479 μm/mm(2); n = 39) EBMD eyes, relative to healthy controls (18,241 ± 4479 μm/mm(2); n = 40) (P < 0.001). Subbasal nerve density in PTK-treated and untreated eyes did not differ (P > 0.05). Epithelial wing cell density did not differ between PTK-treated and untreated EBMD eyes, by either manual or automated analysis; however, epithelial wing cell density in PTK-treated EBMD corneas was significantly reduced (P = 0.008) relative to healthy corneas, by automated cell counting. Subbasal nerve density in EBMD is reduced by 45% and recovers only to the reduced level in the long term after PTK treatment, whereas epithelial wing cell density in EBMD is not affected by PTK in the long term. Fully automated cell analysis from IVCM images could provide an objective, standardized means to quantify and compare corneal cell densities in future studies.

Phototherapeutic keratectomy for treatment of recurrent pterygium

Objective To evaluate the treatment outcomes of excimer laser phototherapeutic keratectomy (PTK) for recurrent pterygium.Methods 106 eyes of 106 patients diagnosed with recurrent pterygium that underwent PTK or autologous limbal stem cell transplantation were retrospectively evaluated.PTK treatment group (53 eyes):Pterygia were treated by separating and excising conjunctiva and pathological tissues.The residual pathological tissues underwent PTK with the Technolas 217z excimer laser.Control group (53 eyes):autologous limbal stem cell transplantation was performed.Data were analyzed for preoperative and postoperative reepitheliation,recurrence rate,and corneal astigmatism.Results The mean reepitheliation time of PTK group was (3.96 ± 0.78) days,and it was significantly shorter than that of control group (4.67 ± 1.01) days (t =-4.071,P ＜ 0.01).The mean postoperative corneal astigmatism in PTK group declined about (0.72 ± 0.80) D comparing to the preoperative one,and the improvement was signifi-cantly more than that of the control group (0.42 ± 0.43 D) (t =-1.342,P =0.02).The mean follow-up time was (18.05 ± 5.32) months.3 cases recurred in PTK group,the recurrence rate was 5.66％ ; 4 cases recurred in control group,the recurrence rate was 7.55％.There was no significant difference in recurrent rate between the two groups (x2 =0.368,P =0.70).Conclusion PTK can be a safe and effective therapeutic alternative for recurrent pterygium.It can avoid excessive operative trauma,hasten reepitheliation,and reduce corneal astigmastism.It can effectively decrease the recurrence rate of pterygium as autologous limbal stem cell transplantation. Key words: Keratectomy, phototherapeutic ; Pterygium; Stem cell, limbal

Effect of TGFβ and PDGF-B blockade on corneal myofibroblast development in mice

The purpose of this study was to investigate the role of transforming growth factor beta (TGFβ) and/or platelet-derived growth factor-B (PDGF-B) blockade on the differentiation of vimentin and alpha-smooth muscle actin (αSMA)-expressing myofibroblasts associated with haze in mice. Mouse corneas had haze-generating irregular PTK (phototherapeutic keratectomy) and topical treatment with the vectors. Six study groups of PTK treated corneas, with four corneas per group in each experiment, were Group 1) treated with TGFβ-KDEL vector interfering with TGFβ signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 2) treated with PDGF-B-KDEL vector interfering with PDGF signaling through anomalous sorting of cytokine bound to the expressed altered receptor; Group 3) treated with both TGFβ-KDEL vector and PDGF-B-KDEL vector to interfere with signaling of both cytokines; Group 4) empty pGFPC1 vector; Group 5) empty pCMV vector; and Group 6) no vector treatment control. At one month after surgery, the corneas were analyzed by immunocytochemistry (IHC) for central stromal cells expressing myofibroblast markers vimentin and αSMA. The stroma of corneas treated with the TGFβ-KDEL vector alone (p < 0.05) or both the TGFβ-KDEL and PDGF-B-KDEL vectors (P < 0.05) had significantly lower density of vimentin-positive cells compared to the corresponding control group. The central stroma of corneas treated with the TGFβ-KDEL vector (p < 0.05) or the PDGF-B-KDEL vector (p < 0.05) had lower density of αSMA-positive cells compared to the corresponding control group. The density of αSMA-positive stromal cells was also significantly lower (p < 0.05) when both the TGFβ-KDEL and PDGF-B-KDEL and vectors were applied together compared to the corresponding control groups. This study provides in situ evidence that TGFβ and PDGF-B have important roles in modulating myofibroblast generation in the mouse cornea after haze-associated injury.

Phototherapeutic keratectomy for the treatment of corneal epithelial ingrowth after laser in situ keratomileusis

目的 探讨激光治疗性角膜切削术(PTK)治疗LASIK术后角膜上皮内生的方法和效果,方法 LASIK术后较严重的角膜瓣下角膜上皮内生4例(4眼),进行内生的上皮刮除和PTK治疗后戴接触镜3～5天,随访10～24个月,结果 4例均治愈,随访期内无复发,视力均恢复至术前最佳矫正视力.眼部刺激症状、眩光消失.结论 LASIK术后瓣下角膜上皮内生,进行角膜瓣后面和角膜床表面的角膜上皮刮除及PTK术,术后戴角膜接触镜,是治疗LASIK术后瓣下角膜上皮内生的有效方法。

Results of Phototherapeutic Keratectomy in the Management of Flap Striae after LASIK before and after Developing a Standardized Protocol: Long-term Follow-up of an Expanded Patient Population

To evaluate the efficacy and safety of phototherapeutic keratectomy (PTK) for treatment of striae in LASIK flaps. Retrospective consecutive series. Forty-seven eyes of 44 patients with flap striae after LASIK with reduced best-corrected visual acuity (VA) or visual symptoms with at least 3 months' follow-up (consecutive cases from January 2001 to May 2004). Transepithelial PTK. Uncorrected VA (UCVA), best spectacle-corrected VA (BSCVA), resolution or reduction of preoperative symptoms, and corneal haze. Mean UCVA and BSCVA improved from 20/43 and 20/29 to 20/33 and 20/23, respectively. Five eyes (10%) developed 1+ haze and 14 eyes (30%) developed trace haze, generally peaking at 1 to 2 months postoperatively. No visual symptoms or loss of acuity were attributable to haze. A mean hyperopic shift of +0.80 diopters (D) occurred after PTK treatment. Development of a standardized protocol significantly reduced the variability of the refractive shift after PTK (P = 0.003). Results were stable in up to 2 years of follow-up. Phototherapeutic keratectomy treatment of LASIK flaps is well tolerated, with stable outcomes and minimal complications. A standardized treatment protocol reduced postoperative refractive variability.

Femtosecond Laser Keratome Creation of Partial Thickness Donor Corneal Buttons for Lamellar Keratoplasty

To evaluate the thickness and diameter accuracy of the IntraLase femtosecond laser in harvesting corneal discs for lamellar keratoplasty. The stromal bed quality of resected corneas was evaluated by scanning electron microscopy. Two IntraLase units were used to create corneal discs at 225-, 300-, 400-, and 500-microm thickness settings and 7-, 8-, 8.5-, and 9-mm diameter settings (n = 28). Achieved thickness was measured using a digital caliper and achieved diameter was measured using imaging software. Samples were preserved and processed for scanning electron microscopy to observe stromal bed quality. On both units, the mean deviation from attempted thickness was -9.5 +/- 8.6 microm (range: +6 to -28 microm). All of the obtained corneal discs were circular (horizontal versus vertical diameters, P > .05). The raster pattern produced a smoother stromal bed compared to the spiral pattern. The IntraLase femtosecond laser keratome provides depth and diameter accuracy even at increased depth settings. Stromal bed was smooth with the raster pattern and can further be smoothed by excimer phototherapeutic keratectomy treatment. Femtosecond laser lamellar keratoplasty is a promising procedure and clinical data are needed to determine effectiveness.

Salzmann's Nodular Degeneration of the Cornea

Salzmann's nodular degeneration is a rare, noninflammatory, slowly progressive, degenerative condition. Bluish-white nodules raised above the surface of the cornea characterize it. It has usually developed in corneas with a history of phlyctenulosis, trachoma, vernal keratoconjunctivitis, measles, scarlet fever, and various other viral diseases. However, today the majority of cases have been seen without recognized previous keratitis. It is composed of dense irregularly arranged collagen tissue with hyalinization between epithelium and Bowman's layer or beyond. Manual removal, phototherapeutic keratectomy (PTK) with or without the use of topical mitomycin-C, lamellar or penetrating keratoplasty have been used in the treatment of this disease. Salzmann's nodular degeneration does not seem to consist of one clinical entity. In some cases, elevated and pannus-like tissue can be separated easily from the corneal surface leaving Bowman's layer almost untouched. In these eyes, subsequent PTK may be necessary to smooth the surface. Recurrences are rare in these eyes. In contrast, some eyes (often with major peripheral vascularization) are left with deep defects in Bowman's layer and superficial stroma after difficult mechanical removal of nodules. In these eyes, multiple masking/laser ablation procedures are mandatory to acquire a homogenous surface. In our experience, the required laser ablation depth is significantly greater and the best-corrected visual acuity to be expected is reduced in contrast to the eyes with easy removal of the nodules. In these eyes recurrences seem to occur more frequently after treatment. Of 35 eyes documented to have Salzmann's nodular degeneration during the last 15 years in our department, 22 needed PTK treatment. Visual acuity increased from 0.4 to 0.7 on average. As a routine, laser ablation should be combined with previous conventional removal of nodules and excessive pannus tissue. By doing so, lamellar and penetrating keratoplasty techniques are hardly ever required in those eyes.

Smoothing of the Ablated Porcine Anterior Corneal Surface Using the Technolas Keracor 217C and Nidek EC-5000 Excimer Lasers

To demonstrate efficacy of a smoothing technique to increase regularity of the anterior corneal surface after photorefractive keratectomy (PRK), using two different excimer lasers. Spherical ablations of -10.00 D were performed on 11 fresh porcine corneas using either the Technolas Keracor 217C scanning-spot or the Nidek EC-5000 scanning-slit beam excimer laser. Following the procedure, we performed a phototherapeutic keratectomy treatment (smoothing technique) on half of the corneal surface. The smoothing technique was performed using a viscous solution of 0.25% sodium hyaluronate, which was spread on the cornea prior to the procedure. The ablation zone was 6 mm in diameter and the transition zone extended to 3 mm. The ablation depth was set at 10 microm. Corneas were then examined with scanning electron microscopy. Smoother treatment zones were apparent in porcine corneas in which smoothing was performed following PRK, with both laser systems. Results from the two lasers were not directly compared. The smoothing procedure performed following PRK using a viscous 0.25% sodium hyaluronate masking solution and a scanning laser system rendered the porcine corneal surface more regular.

187 The role of 3rd therapy in recurrent ovarian carcinoma or primary peritoneal carcinoma

Purpose: To evaluate the outcome of excimer laser phototherapeutic keratectomy (PTK) for recurrent corneal erosion.Setting: Laser Institute, Assaf Harofeh Medical Center, Zerifin, Israel.Methods: Twenty-three patients with a mean age of 50.56 years ± 13.87 (SD) were referred between 1991 and 1995 for recurrent corneal erosion that did not respond to conservative treatment. All were treated by excimer laser PTK. Patients were interviewed and examined before and after treatment.Results: Disease duration ranged from 2 months to 10 years. Frequency of attacks ranged from weekly to three to four times a year. Re-epithelialization of the cornea was established within an average of 3 days after PTK treatment. Follow-up was 12 to 60 months (mean 38.43 ± 14.08 months). Nineteen (83%) patients were free of recurrences, and 3 had one recurrence treated successfully by patching. One patient who had two recurrences had a second PTK procedure and was symptom free for 14 months. No patient reported reduced visual acuity or quality. Postoperative best corrected visual acuity was unaltered in 21 eyes and improved in 2. There was no significant difference between preoperative and postoperative manifest refractions.Conclusion: Excimer laser PRK appears to be a safe and effective treatment for recurrent erosions of the cornea.

Phototherapeutic keratectomy versus diamond burr polishing of Bowman’s membrane in the treatment of recurrent corneal erosions associated with anterior basement membrane dystrophy

PurposeTo compare the efficacy of phototherapeutic keratectomy (PTK) to epithelial debridement and polishing of Bowman’s membrane using a diamond burr (DB) in the treatment of recurrent corneal erosions associated with anterior basement membrane (ABM) dystrophy. DesignRetrospective nonrandomized comparative trial. MethodsMedical records of 39 patients (42 eyes) who underwent a PTK or DB procedure for recurrent corneal erosions associated with ABM dystrophy between March 1992 and June 2000 were reviewed. History of injury, prior treatment received, and the corneal slit-lamp findings were noted in all patients. In both procedures, all loose epithelium was completely removed. In PTK patients, 5 μm of Bowman’s membrane was ablated with the excimer laser. In patients who underwent DB treatment, a hand-held battery-driven diamond dusted burr was used to gently and uniformly polish Bowman’s membrane in the area of the epithelial defect. Main outcome measuresSymptomatic improvement, recurrence of painful erosions, development of haze, and change in the visual acuity. Statistical analysis was performed for comparison of data between the two groups. ResultsFifteen eyes of 14 patients underwent PTK, and 27 eyes of 25 patients underwent epithelial debridement and DB treatment. In the PTK group, mild haze was seen in five (35.7%) eyes. Recurrence of painful erosions was seen in four eyes (26.7%). The mean follow-up was 17.6 ± 5.7 months (range, 0.7–81.9 months). Best-corrected visual acuity was better in five eyes (35.7%) after the procedure and the same in nine eyes (64.3%). In the DB group, mild haze was seen in seven eyes (25.9%). Recurrence of painful erosions was seen in three eyes (11.1%). The mean duration of follow-up was 6.7 months (range, 1–24.2 months). Best-corrected visual acuity was better in 3 eyes (14.3%), the same in 17 eyes (81%), and worse in 1 eye (4.8%) after the procedure. Final visual acuity was not available for one eye in the PTK group and 6 eyes in the DB group. There was no statistically significant difference in haze (Fisher’s exact test, P = 0.38), recurrence of erosions (Kaplan-Meier analysis with log rank, P = 0.73), and vision being better or the same (Fisher’s exact test, P = 0.6) between the PTK and DB groups. ConclusionsBoth PTK and DB treatment are effective methods of treating recurrent corneal erosions associated with ABM dystrophy. Diamond burr treatment, being a simpler, less expensive office procedure with a tendency toward lesser incidence of haze and recurrence in this study, seems to have advantages over PTK in the treatment of recurrent corneal erosions. Further prospective studies are required to confirm the long-term efficacy of DB treatment in the management of recurrent corneal erosions associated with ABM dystrophy.

Phototherapeutic keratectomy of a corneal scar due to presumed infection after photorefractive keratectomy

This case involves a 25-year-old patient who suffered from corneal ulceration several days after photorefractive keratectomy (PRK). A central scar developed, resulting in discomfort and reduction in visual acuity. Four months later, the scar was treated by phototherapeutic keratectomy (PTK) (25 μm depth, 5 mm ablation zone). Some scar tissue was left, but it cleared slowly and steadily over the next few years. The induced hyperopia decreased from 5.00 to 1.37 diopters spherical equivalent within 28 months postoperatively. Best corrected visual acuity increased from 20/60 preoperatively to 20/20 at 28 months postoperatively. Surgeons can encourage patients with postinfectious scars after PRK to try at least 1 PTK treatment.