Amniotic Membrane Graft with Argon Laser Photocoagulation Versus Amniotic Membrane Graft with Tissue Debridement for Treatment of Mycotic Keratitis

Aim: To compare augmented therapy with argon laser and amniotic membrane graft (AMG) versus AMG and tissue debridement for resistant mycotic corneal ulcers. Methods: This study included 40 cases of resistant fungal corneal ulcers in two groups. In one group, argon laser photocoagulation and AMG were done while AMG with tissue debridement was done as adjunctive therapy for the specific antifungal agents. Results: Complete healing with no adverse effects was achieved in argon laser group in duration ranging from 2-3 weeks in all cases. In the AMG group, duration of healing ranged from 3-5 weeks. Visual acuity was improved with one or more line gain in eight cases (40%) in the laser group, while in six cases (30%) only in the AMG group. Conclusions: Augmented therapy with argon laser and AMG is superior to AMG with tissue debridement for treatment of resistant fungal corneal ulcers.     

Randomised clinical trial evaluating best-corrected visual acuity and central macular thickness after 532-nm subthreshold laser grid photocoagulation treatment in diabetic macular oedema

Purpose

To compare best-corrected visual acuity (BCVA) and central macular thickness (CMT) after 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation for the treatment of diabetic macular oedema (DME).

Patients and methods

Twenty-three patients (46 eyes) with binocular DME were enroled in this study. The two eyes of each patient were divided into a subthreshold photocoagulation group and a threshold photocoagulation group. The eyes of the subthreshold group underwent 532-nm patter scan laser system (PASCAL) 50% end point subthreshold laser grid photocoagulation therapy, whereas the threshold photocoagulation group underwent short-pulse grid photocoagulation with a 532-nm PASCAL system. BCVA and CMT were assessed in all patients before treatment, 7 days after treatment, and 1, 3, and 6 months after treatment.

Results

After grid photocoagulation, the mean BCVA improved in both the subthreshold group, and the threshold group, and the two groups did not differ statistically significantly from each other. Similarly, the macular oedema diminished in both groups after treatment, and the two groups did not differ statistically significantly from each other with regard to CMT.

Conclusion

Both 532-nm subthreshold laser grid photocoagulation and threshold laser grid photocoagulation can improve the visual acuity and reduce CMT in DME patients.     

Effects of Argon Laser Iridotomy on the Corneal Endothelium of Pigmented Rabbit Eyes

Purpose

In Asian countries, laser iridotomy for the treatment of angle-closure glaucoma is a common cause of bullous keratopathy, which may be associated with a shallow anterior chamber and dark iris pigmentation in Asians. Several cases of corneal decompensation after argon laser iridotomy have been reported. In the present study, we evaluated the harmful effects of argon laser iridotomy on the corneal endothelium.

Methods

Argon laser iridotomy was performed on the right eyes of pigmented rabbits. Changes in corneal thickness and endothelial cell density after laser iridotomy were evaluated. Terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) was performed for assessment of corneal endothelial cell apoptosis. Combined staining with alizarin red and trypan blue, as well as a live/dead cell assay, were performed for evaluation of damage to the corneal endothelium induced by laser iridotomy.

Results

Corneal thickness did not change immediately after laser iridotomy; however, a significant increase was observed 24 hours after iridotomy (p = 0.001). The endothelial cell density of laser-treated eyes four days after laser iridotomy was significantly decreased compared with control eyes (p < 0.001). TUNEL staining showed many TUNEL-positive cells in the corneal endothelium and corneal stroma. No endothelial trypan blue-stained cell nuclei were observed after laser iridotomy; however, several large endothelial cells with damaged membrane integrity were observed. The live/dead cell assay clearly showed a large number of dead cells stained red in several areas throughout the entire corneal button 24 hours after iridotomy.

Conclusions

Argon laser iridotomy induces corneal endothelial cell apoptosis in pigmented rabbit eyes, resulting in decreased endothelial cell density.     

Aniridia Associated with Lens Coloboma and Secondary Glaucoma Treated with Transcorneal Argon Laser Ciliary Body Photocoagulation: A Case Report

Purpose

The aim of this study is to describe the management of cataract and refractory glaucoma in a case of congenital aniridia (AN)-1.

Methods

In an 18-year-old female patient affected by congenital AN, bilateral coloboma of the zonula and lens, cataract and glaucoma, pars plana vitrectomy, cataract extraction and subsequent transcorneal ciliary body argon laser photocoagulation were performed.

Results

Five years after laser treatment, the best-corrected visual acuity was 20/50 and the intraocular pressure was stable at 18 mm Hg with topical pharmacological management consisting of timolol 0.5% and latanoprost 0.005%.

Conclusions

From our experience, transcorneal ciliary body photocoagulation after cataract extraction and vitrectomy could be a useful technique to manage high ocular pressure in eyes affected by congenital AN.Key words: Aniridia, Glaucoma, Limbal stem cell deficiency, Congenital aniridia, Lens coloboma, Transcorneal ciliary body photocoagulation     

Queratitis micótica causada por Scedosporium apiospermum en paciente inmunocompetente

Clinical case

A 51 year-old immunocompetent male was referred due to presenting with a large corneal ulcer with hypopyon in the right eye. Topical amphotericin B, fluconazole and moxifloxacin, as well as oral itraconazole were initially indicated. Following the report of mycotic structures on staining, topical natamycin was started. The result of the culture was reported two weeks later as, Scedosporium apiospermum (S. apiospermum), and topical voriconazole was then added. The response to treatment was very slow, and took five weeks after receiving triple therapy (natamycin, voriconazole and fluconazole) and one dose of intrastromal voriconazole, for the hypopyon to disappear. The final outcome was successful, achieving healing of the ulcer. The patient is waiting for a corneal transplant.

Combination of Intravitreal Ranibizumab and Laser Photocoagulation for Aggressive Posterior Retinopathy of Prematurity

Purpose

To report on 2 cases of aggressive posterior retinopathy of prematurity (ROP) treated with intravitreal ranibizumab (Lucentis^®) and laser photocoagulation.

Methods

Two premature females, born at 25 and 26 weeks’ gestation with a birth weight of 530 and 550 g, respectively, with aggressive posterior ROP received combined treatment with laser photocoagulation and intravitreal ranibizumab (0.3 mg [30 µl]) to each eye. Structural outcomes were evaluated by indirect ophthalmoscopy and documented by retinography.

Results

An intravitreal injection was made at 34 weeks of postmenstrual age in the first case, followed by laser photocoagulation 1 week later. There was a partial regression of ROP with treatment. Five weeks later, neovascularization regrowth with bleeding in both eyes (intraretinal and subhyaloid) occurred and retreatment with combined therapy was performed. In the second case, single therapy with laser photocoagulation was made at 34 weeks of postmenstrual age. In spite of the confluent photocoagulation in the avascular area, progression to 4A ROP stage occurred 1 week later. Both eyes were retreated 1 week later with intravitreal ranibizumab and laser photocoagulation. Treatment resulted in ROP regression in both cases. There were no signs of systemic or ocular adverse side effects.

Conclusion

The cases presented show that combination therapy of indirect laser photocoagulation and intravitreal ranibizumab can be effective in the management of aggressive posterior ROP. Further investigation on anti-VEGF safety in premature infants is necessary. Additional studies are needed to define the role of anti-VEGF in ROP treatment.Key Words: Retinopathy of prematurity, Laser photocoagulation, Ranibizumab, Anti-VEGF therapy     

Spectrum of fungal keratitis:clinicopathologic study of 44 cases

AIM:To determine the causative agents of fungal keratitis and study the predisposing factors over a period of ten years in a single tertiary care hospital.METHODS:A retrospective analysis of fungal corneal ulcers was done from 2003-2012. Patients’ clinical data were noted from the file records. Correlation of histopathological diagnosis was done with the report on fungal culture.RESULTS: Mycotic keratitis was established in 44 cases by a positive fungal culture. Direct microscopic examination of potassium hydroxide (KOH) mounts revealed fungal elements in 39 cases while 40 cases showed fungus on Gram stained smears. Males (54.55%) were more commonly affected than the females (45.45%). The age ranged from 18 to 82 years. Most common age group to be involved was 41-60 years. Predisposing risk factors were seen in 34 (77.27%) cases. Most common findings on clinical examination were anterior chamber reaction and conjunctival injection seen in all the cases. Other common findings were stromal infiltration and hypopyon seen in 20 (45.45%) and 18 (40.91%) cases respectively. On histopathological examination the fungus was typed, as aspergillus in 34 cases while no definite typing was possible in 10 cases. The predominant isolate was aspergillus flavus (59.09%) followed by fusarium (15.91%). Mixed fungal and bacterial infection was seen in 3 (6.82%) cases.CONCLUSION:Although culture is the gold standard for definitive diagnosis of fungal keratitis, direct microscopic examination of corneal scrapings or histomorphological evaluation of biopsies allow a rapid preliminary diagnosis. Early administration of antifungal treatment helps in preventing dreadful complications.     

The Anti-angiogenic Effect of Chlorogenic Acid on Choroidal Neovascularization

Purpose

To evaluate the inhibitory effect of chlorogenic acid on laser-induced choroidal neovascularization (CNV) in a rat model.

Methods

Intraperitoneal injection of chlorogenic acid (10 mg/kg) was inititated one day prior to laser photocoagulation and continued for eight days. Eyes were removed 14 days after laser photocoagulation. Fluorescein angiography was employed at seven and 14 days to assess the CNV lesions, and histological examination was performed. Quantification of CNV size and leakage were performed both in histological sections and fluorescein angiography in order to compare the inhibitory effects of chlorogenic acid on CNV with the results of the control.

Results

Histological analysis showed no significant difference in CNV size between the treated and control groups. However, CNV leakage on fluorescein angiography had significantly decreased in the chlorogenic acid-treated group at 14 days after laser photocoagulation compared with that of the control group. In addition, CNV size on fluorescein angiography had significantly decreased in the treated group at seven and 14 days.

Conclusions

These results suggest that chlorogenic acid has anti-angiogenic effects on CNV and may be useful as an inhibitor in the treatment or prevention of neovascular age-related macular degeneration.     

Pascal laser versus conventional laser for treatment of diabetic retinopathy

Purpose

To compare the safety and efficacy of Pascal laser photocoagulation in comparison with the conventional laser photocoagulation in the treatment of diabetic retinopathy.

Patients and methods

A prospective randomized case series study was done on 120 procedures done in 120 patients divided into two main groups, group A, patients undergoing focal or modified grid macular laser and group B, patients undergoing panretinal photocoagulation (PRP). Each of the two groups were subdivided into two subgroups randomly in the first we used conventional laser photocoagulation (groups A1 and B1) and in the other we used Pascal laser photocoagulation (groups A2 and B2).

Results

Procedures in groups A1,2 and in groups B1,2 had successful outcomes. Significantly higher powers were required with the Pascal (groups A2 and B2) than with conventional laser (groups A1 and B1) (p < 0.001) in eyes that underwent PRP and focal/modified grid macular treatment with both systems. No adverse events were noted in all groups.

Conclusion

The Pascal photocoagulator is safe, rapid, effective, with rapid learning and had short exposure time. Although the shorter pulse duration of the Pascal necessitates the use of a higher power, it is not associated with adverse effects.     

Outcome of complete intrastromal ring implantation using femtosecond laser in pellucid marginal degeneration

Purpose

To evaluate the effect of complete intrastromal corneal ring implantations on patients with pellucid marginal degeneration (PMD).

Design

Prospective interventional case series

Patients and Methods

Thirty-three eyes with PMD were included into the study. After pocket creation with femtosecond laser (Femtec; 20/10 PerfectVision), MyoRing implantation was performed. Uncorrected and corrected distance visual acuity (UDVA, CDVA), subjective refraction, keratometry, central corneal thickness, corneal biomechanical profile (Ocular Response Analysis), and whole-eye wavefront aberrometry (iTrace) were evaluated preoperatively and also postoperatively, 1 month, 3 months, 6 months, and 1 year after the operation.

Results

One month after surgery, significant improvements were observed in UDVA (ANOVA; P=0.02), mean keratometry, sphere (ANOVA; P <0.001), and cylinder (ANOVA; P=0.04) with no significant changes afterwards. No significant change occurred in the corneal biomechanical profile. Primary coma and trefoil reduced after 1 year (ANOVA; P values were 0.02 and 0.06, respectively). Primary spherical aberration significantly increased according to the 1-year follow-up (ANOVA; P<0.001). No significant complication was observed.

Conclusion

MyoRing is considered as a treatment modality for spherocylindrical correction in patients with PMD, with an acceptable safety and efficacy profile.     

Mycotic corneal ulcers in upper Assam

Purpose:

To study the association of various risk factors and epidemiological variables of mycotic keratitis treated at a tertiary referral hospital of upper Assam.

Materials and Methods:

In this hospital-based prospective study a total of 310 consecutive corneal ulcer cases attending the ophthalmology outpatient department of Assam Medical College were enrolled between April 2007 and March 2009. After clinical and slit-lamp biomicroscopic examination in all suspected cases, smears and culture examination for fungus was done to establish the etiology. Demographic information and associated probable risk factors of individual cases were noted in a predesigned questionnaire.

Results:

In 188 (60.6%) cases fungal etiology could be established. Out of them 67.6% were males. The most commonly affected age group was 41-50 years (25.5%). The maximum (23.4%) cases were reported during the paddy harvesting season in Assam (January and February). Fungal element could be demonstrated in 65.2% cases in direct potassium hydroxide (KOH) mount. The commonest predisposing factor was corneal injury (74.5%). While diabetes was a significant systemic predisposing factor in mixed bacterial and fungal infections in 11.1% cases, blocked naso-lacrimal duct was the local predisposing factor in 11.1% of cases. Fusarium solani (25%) was the commonest isolate followed by Aspergillus species (19%), Curvularia species (18.5%) and Penicillium species (15.2%). Yeasts were isolated in 2.7% (n=5) cases.

Conclusions:

Ocular trauma was the commonest cause of fungal corneal ulcer in Assam and Fusarium solani was the commonest species responsible for it. Most of the mycotic ulcer cases come from rural areas including the tea gardens.     

Corneal Chromoblastomycosis Caused by Fonsecaea pedrosoi

Purpose

To report 2 unusual cases of fungal keratitis due to Fonsecaea pedrosoi.

Methods

Two patients were diagnosed with Fonsecaea pedrosoi keratitis. Their files were reviewed for predisposing factors, clinical characteristics, microbiological study, treatment, and outcome.

Results

Two consecutive patients presented with brownish pigmented corneal ulcers in their eyes after sustaining eye trauma from vegetative matter. In both cases, corneal scrapings were collected for microscopic examination and culture. Dematiaceous hyphae were seen on the smears, and dark pigmented colonies grew on the culture media, identified as F. pedrosoi. Both patients were treated and cured with combined topical antifungal agents and oral itraconazole. The first patient required an amniotic membrane patch, while the second received an intracameral amphotericin B injection.

Conclusions

Pigmented infiltrates can be an important diagnostic clue, but a microscopic evaluation and culture are required to obtain an accurate diagnosis of Fonsecaea keratitis. The prompt diagnosis and combined antifungal treatment can prevent morbidity associated with this fungal infection.Key Words: Fonsecaea pedrosoi, Dematiaceous fungus, Keratitis, Chromoblastomycosis     

A Three-year Follow-up of Intravitreal Triamcinolone Acetonide Injection and Macular Laser Photocoagulation for Diffuse Diabetic Macular Edema

Purpose

To report the three-year outcomes of macular laser photocoagulation following intravitreal injection of triamcinolone acetonide (IVTA) for diffuse diabetic macular edema (DME).

Methods

A prospective, randomized controlled study was completed. Eighty-six eyes of 74 patients with diffuse DME were randomized into two groups. Eyes assigned to the combination group (n = 48) were subjected to macular laser photocoagulation three weeks after IVTA. Eyes in the IVTA group (n = 38) underwent IVTA alone. Central macular thickness was measured by optical coherence tomography, and the number of additional treatments and mean time to recurrence were assessed.

Results

Thirty-seven eyes in the combination group and 26 eyes in the IVTA group completed the three-year follow-up. Recurrence of DME after initial treatment was not observed for nine of the 37 (24.3%) eyes in the combination group or for one of the 26 (3.9$) eyes in the IVTA group (p = 0.028). DME was absent for 19.9 months after treatment in the combination group compared to 10.3 months in the IVTA group (p = 0.027). The mean number of additional treatments was 0.92 in the combination group and 1.88 in the IVTA group (p = 0.001).

Conclusions

Results in the subset of subjects who completed the three-year follow-up demonstrated that laser photocoagulation following IVTA is more effective than IVTA monotherapy for diffuse DME. Combination therapy required fewer additional treatments and resulted in a lower recurrence rate than IVTA monotherapy.     

Gas tamponade combined with laser photocoagulation therapy for congenital optic disc pit maculopathy

Purpose

To evaluate the long-term clinical efficacy and safety of gas tamponade combined with laser photocoagulation for optic disc pit maculopathy.

Methods

Seven consecutive patients with unilateral maculopathy associated with optic disc pit and one patient with bilateral optic disc pit maculopathy were given octafluoropropane (C₃F₈) tamponade combined with focal laser photocoagulation treatment. Patients were followed up for 21–62 months after treatment. Main outcomes were determined by optical coherence tomography (OCT) and best-corrected visual acuity (BCVA).

Results

Treatment with C₃F₈ tamponade followed by laser photocoagulation in ODP maculopathy patients resulted in resolution of sub-retinal and/or intra-retinal fluid in six out of eight patients. The remaining two patients had significant reduction in fluid, as determined by OCT, and funduscopy, as well as an improvement in anatomical architecture. Visual acuity improved obviously in seven eyes and remained stable in two eyes. Central visual field loss after photocoagulation was not clinically appreciable by visual field examination. No post-operative complications of maculopathy occurred during the follow-up period.

Conclusions

Although repeated treatment was needed in some patients, C₃F₈ tamponade combined with laser photocoagulation is still a simple, effective, minimally invasive, and economic therapy for optic disc pit maculopathy.     

Incidence and microbiological profile of mycotic keratitis in a tertiary care eye hospital: A retrospective analysis

Purpose

To determine the incidence and microbiological profile of mycotic keratitis seen at a tertiary care eye hospital.

Materials and methods

A retrospective review of microbiology records of patients presenting with suspected microbial keratitis seen between January 2006 and December 2009 was performed. Patients with positive fungal cultures were further analyzed for the type of fungus isolated and associated bacterial pathogens.

Results

Microbiology records of 2300 patients with suspected microbial keratitis were reviewed. A microbiological diagnosis of mycotic keratitis was established in 87 (3.8%) patients over a four year period based on positive fungal cultures. The yearly incidence of mycotic keratitis was 3.2% (2006), 4.9% (2007), 3.3% (2008) and 3.6% (2009). Filamentous fungi were isolated more often than yeasts. Aspergillus species followed by Fusarium species and Trichophyton species were the commonest filamentous fungi isolated while Candida albicans was the most frequently encountered yeast. Mixed infections due to fungal and bacterial pathogens were seen in 25/87 (28.7%) patients.

Conclusion

Cumulative incidence of mycotic keratitis was 3.8% over a four year period. Aspergillus species and Candida albicans were the most frequent pathogenic organisms causing mycotic keratitis in this part of the world. Mixed infections were seen in 28.7% of the patients. Knowledge of the “local” etiology within a region may be valuable in the management of mycotic keratitis in instituting an empirical therapy, especially when facilities for microscopy, cultures and antifungal susceptibility are not readily available. The baseline information presented will also be helpful in the planning of a corneal ulcer management strategy and for future studies on mycotic keratitis.     

Neovascular Glaucoma Induced by Peripheral Retinal Ischemia in Neurofibromatosis Type 1: Management and Imaging Features

Purpose

To report the case of a young patient affected by neurofibromatosis 1 (NF-1) with peripheral retinal ischemia-induced neovascular glaucoma and the peculiar spectral-domain optical coherence tomography (SD-OCT) features.

Material and Methods

A 13-year-old boy affected by NF-1, as diagnosed according to established criteria, was referred with a diagnosis of hypertensive uveitis in his left eye. He underwent a complete ophthalmic examination and comprehensive blood work with viral and immunological tests. The case was documented with fluorescein angiography (FA) and SD-OCT. When the intraocular pressure (IOP) of the left eye decreased and the cornea cleared, FA revealed retinal ischemia and leakage from pathologic retinal vessels. SD-OCT revealed foveal hypoplasia secondary to the complete absence of the retinal nerve fiber layer.

Results

Peripheral retinal ischemia-induced neovascular glaucoma was diagnosed. The patient underwent Ahmed valve implantation to control his IOP, and subsequent retinal photocoagulation by argon laser and intravitreal bevacizumab injection were performed to control neovascularization.

Discussion

Retinal ischemia in NF-1 might lead to neovascular glaucoma: lowering of the IOP with surgical implantation of an Ahmed valve, regression of neovascularization by argon laser panretinal photocoagulation and intravitreal injection of bevacizumab can be a helpful way to control such a complication.Key words: Neovascular glaucoma, Neurofibromatosis, Retinal ischemia     

Clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis

AIM: To study the clinical observation of removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis. METHODS：A retrospective study was done to 10 patients (10 eyes) who had accepted removal of the necrotic corneal tissue combined with conjunctival flap covering surgery for fungal keratitis,the diagnosis by corneal scraping and smear examination or confocal microscopy check hyphae.Local and systemic antifungal therapy more than one week for all patients, corneal ulcer enlarge or no shrink.Slit lamp microscope examination the diameter of corneal ulcer about 2mm-4mm.Anterior segment optical coherence tomography（AS-OCT）examine the depth of corneal ulcer between 1/3-1/2,infiltrate corneal stroma about 20um-80um,the diameter of corneal ulcer about 3mm-6mm.Type-B ultrasonic exclusion endophthalmitis. Complete removal lesions until transparent of stroma, make conjunctival flap equal or greater than ulcer 1mm nearby conjunctiva. Continued antifungal therapy. The vision, fungal recurrence, conjunctival flap rollback or desquamate were analysed. RESULTS：Ten patients had success done this surgery, the corneal ulcer was not enlarge and healing afteroperation.7 cases were bridging conjunctival flap and 3cases were single conjunctival flap. Preoperation vision above 0.1 had 8 cases,7 cases had vision above 0.1 one week after surgery, while 1 cases vision droped from 0.3 to 0.05.There was not recurrent for fungal,2 cases conjunctival flap rollback:1 case was bridging and 1case was single flap, no conjunctival flap desquamate. CONCLUSION：It is safe and effective to perform removal of the necrotic corneal tissue combined with conjunctival flap covering surgery under the guidance of the AS-OCT in treatment of fungal keratitis which werenot sensitive or aggravate for antifungal drugs.     

The Effect of Bevacizumab versus Ranibizumab in the Treatment of Corneal Neovascularization: A Preliminary Study

Purpose

To compare the short term effects of bevacizumab and ranibizumab injections on the regression of corneal neovascularization (NV).

Methods

Sixteen eyes of 16 patients with corneal NV were randomly assigned for an injection with 2.5 mg of bevacizumab (group 1, n = 8) or 1 mg of ranibizumab (group 2, n = 8) through subconjunctival and intrastromal routes. The patients were prospectively followed-up for one month after the injections. Corneal NV areas, as shown on corneal slit-lamp photographs stored in JPEG format, were calculated using Image J software before the injection, one week after the injection, and one month after the injection. The corneal NV areas were compared before and after the injections.

Results

Seven women and nine men, with an average age of 51 years, presented with corneal NV secondary to herpetic keratitis (7 cases), graft rejection (6), chemical burn (1), pemphigoid (1), and recurrent ulcer (1). In group I, the preoperative corneal NV area (8.75 ± 4.33%) was significantly decreased to 5.62 ± 3.86% one week after the injection and to 6.35 ± 3.02% one month after the injection (p = 0.012, 0.012, respectively). The corneal NV area in group 2 also exhibited a significant change, from 7.37 ± 4.33% to 6.72 ± 4.16% one week after the injection (p = 0.012). However, no significant change was observed one month after the injection. The mean decrease in corneal NV area one month after injection in group 1 (28.4 ± 9.01%) was significantly higher than in group 2 (4.51 ± 11.64%, p = 0.001).

Conclusions

Bevacizumab injection resulted in a more effective and stable regression of corneal NV compared to the ranibizumab injection. The potency and dose of these two drugs for the regression of corneal NV require further investigation.     

Ultrastructural pathology of corneal neovascu-larization after photodynamic therapy in rabbits

AIM: To investigate the ultrastructural pathogenesis of photodynamic therapy (PDT) for the experimental corneal neovascularization (CNV) by Hematoporphyrin Derivate (HPD) as photosensitizer and Argon laser as light source. METHODS: Experimental CNV models were induced in 7 white rabbits using alkali burn. Six weeks after models establishment, animals with CNV were injected with HPD intravenously, and 48 hours after the injection, 7 eyes were irradiated with argon laser (power 800mw, wavelength 514.5nm, spot diameter 200μm, exposure time 2ms). The irradiated CNV was observed by light microscopy and scanning electron microscopy. RESULTS: Histopathological study indicated that there was a striking decrease in the number of the CNV, vascular endothelium became degeneration and necrosis, some vessels were atrophy and attenuated, and vessels cavity were blocked by some thrombosis. No obvious abnormal histopathological findings were noted in surrounding tissues. CONCLUSION: The high precise action on CNV and minimal damage to surrounding tissues with PDT by HPD as photosensitizer suggested that PDT might be an effective and safe modality in the treatment of CNV.     

Changes in Spherical Aberration after Various Corneal Surface Ablation Techniques

Purpose

The corneal change induced by refractive procedures influence both the postoperative refractive status and the ocular spherical aberration (SA). We evaluated changes in corneal SA after three types of surface ablation: phototherapeutic keratectomy (PTK), myopic photorefractive keratectomy (PRK), and myopic wavefront-guided laser epithelial keratomileusis (LASEK).

Methods

Twenty-six eyes (25 patients) were subjected to PTK 26 eyes (14 patients) to PRK, and 34 eyes (17 patients) to wavefront-guided LASEK. Corneal SA was measured with the iTrace in all patients both preoperatively and 6 months postoperatively.

Results

Six months after surgery, mean corneal SA was -0.173 ± 0.171 µm in the PTK group, 0.672 ± 0.200 µm in the PRK group, and 0.143 ± 0.136 µm in the wavefront-guided LASEK group. The mean difference between the preoperative and postoperative corneal SA (ΔSA) was -0.475 µm in the PTK group, 0.402 µm in the PRK group, and -0.143 µm in the wavefront-guided LASEK group.

Conclusions

Surgically induced changes in corneal SA vary with procedure. The prediction of the pattern of SA change induced by various surface ablation procedures may be helpful for developing future surgical procedures.