Evaluation of techniques of single continuous suturing in penetrating keratoplasty

AIM

To evaluate the three techniques of single continuous suturing-namely, torque, antitorque, and no torque in penetrating keratoplasty.

METHODS

53 eyes of 53 patients underwent penetrating keratoplasty using torque (17 patients), antitorque (18 patients), and no torque (18 patients) suturing techniques in this prospective study. Patients were followed up at 4 weeks, 3 months, and 6 months. Keratometric, videokeratographic, refractive astigmatism, and best corrected visual acuity were determined in all the three groups at each follow up visit. Post-keratoplasty suture adjustment was done at 4 weeks, if the astigmatism was >3 dioptres.

RESULTS

The initial astigmatism in the torque group was higher than in the other two groups, although it was not statistically significant. Following suture adjustment, there was a significant decrease in astigmatism in all the three groups (p<0.0001). However, no significant difference in the postoperative astigmatism at 3 months and at 6 months was seen among the three groups.

CONCLUSIONS

The three techniques of single continuous suturing-that is, torque, antitorque, and no torque produce a similar final astigmatic results. Suture adjustment is an effective method of reducing post-penetrating keratoplasty astigmatism.

Outcome of extracapsular cataract surgery plus posterior chamber intraocular lens insertion for age-related cataract in eastern Nepal

As age-related cataract is the leading cause of blindness in Nepal, much more attention should be given to improving surgical outcomes. The aim of our study was to determine the effectiveness and risks of extracapsular cataract surgery (ECCE) for age-related cataract in a tertiary hospital of eastern Nepal. ECCE with posterior chamber intraocular lens (PC IOL) insertion on 797 eyes (754 patients) revealed improved visual acuity in 97.9%. In 595 (74.6%) the best corrected visual acuity was 6/18 or better, and 167 (20.9%) had 6/24 to 6/60 with negligible operative/postoperative complications. Thus it is concluded that ECCE with PC IOL could be performed safely and effectively even in developing countries where people are unaware that surgery is available and of the good surgical outcome.

Therapy of acanthamoeba keratitis--an experimental study

The study was conducted to determine the efficacy of various drugs/agents in the treatment of experimentally induced Acanthamoeba Keratitis (A. keratitis). Thirty rabbits were divided into 5 equal treatment groups and polyhexamethylene biguanide (PHMB) 0.02%, fluconazole 0.2%, povidone iodine 5%, aprotinin 40 IU/ml and normal saline were administered in a double blind manner, at a dose of one drop, 5 times/day. Neomycin 1700 U/ml was used as a common drug in all groups, with same frequency. Post therapy subsidence of lid oedema, mucopurulent discharge, conjunctival congestion, corneal epithelial defect and anterior chamber reactions were noted. Average healing time in days (Mean +/- S.D.) were 13.67 +/- 1.21, 22 +/- 1.41, 23.5 +/- 1.05, 17.0 +/- 1.41 and 28.0 +/- 1.90 for PHMB, fluconazole, povidone iodine, aprotinin and normal saline respectively. Lid oedema, mucopurulent discharge and conjunctival congestion improved faster in PHMB and aprotinin treated eyes. The results of this study suggest that PHMB is a better drug for A. keratitis, while aprotinin may be used as an adjuvant drug in the management of A. keratitis.

Endothelial dysfunction does not require loss of endothelial nitric oxide synthase

Whereas altered nitric oxide (NO.) formation from endothelial nitric oxide synthase (NOS) causes impaired vascular reactivity in a number of cardiovascular diseases, questions remain regarding how endothelial injury results in impaired NO. formation. It is unknown if loss of NOS expression or activity is required or if other factors are involved. Detergent treatment has been used to induce endothelial dysfunction. Therefore, NOS and NO. synthesis were characterized in a rat heart model of endothelial injury and dysfunction induced by the detergent Triton X-100. Cardiac NO. formation was directly measured by electron paramagnetic resonance spectroscopy. NOS activity was determined by the L-[(14)C]arginine conversion assay. Western blots and immunohistology were applied to define the amounts of NOS present in heart tissue before and after Triton treatment. Immunoelectron microscopy was performed to assess intracellular NOS distribution. A short bolus of Triton X-100, 0.25%, abolished responses to histamine and calcium ionophore while preserving response to nitroprusside. Complete blockade of NO. generation occurred after Triton treatment, but NOS activity assayed with addition of exogenous substrate and cofactors was unchanged, and identical 135-kDa NOS bands were seen on Western blots, indicating that NOS was not removed from the heart or structurally damaged by Triton. Immunohistochemistry showed no change in NOS localization after Triton treatment, and immunoelectron microscopy revealed similar NOS distribution in the plasma membrane and intracellular membranes. These results demonstrate that the endothelial dysfunction was due to decreased NO. synthesis but was not caused by loss or denaturation of NOS. Thus endothelial dysfunction due to mild endothelial membrane injury may occur in the presence of active NOS and is triggered by loss of NOS substrates or cofactors.

Massive corneal and conjunctival squamous cell carcinoma

A patient with massive, protuberant squamous cell carcinoma of conjunctiva invading the whole cornea, so as to hang from the surface, was referred with a visual acuity of hand motion near to face. A microscopically-controlled, frozen section guided excision, followed by double-freeze-thaw cryoapplication to the sclera and the edges of the conjunctival bed and lamello-lamellar sclerokeratoplasty, was performed. Three years later the patient's visual acuity was 20/60 with no evidence of recurrence of the lesion. Frozen section guided excision with adjuvant cryotherapy and lamellar sclerokeratoplasty is a viable therapy for massive squamous cell carcinoma of cornea and conjunctiva.

Intralamellar dissection techniques in lamellar keratoplasty

PURPOSE

To evaluate and compare the efficacy of the four adjunctive agents to facilitate recipient bed intralamellar dissection in cases of lamellar keratoplasty.

METHODS

Forty eyes with partial-thickness corneal opacities were recruited for this prospective, randomized clinical trial. The cases were divided into four groups per the intralamellar injection (i.e., air [group I], 2% hydroxypropyl methylcellulose [HPMC] [group II], balanced saline solution [BSS] [group III], and no adjunct [group IV] used to facilitate recipient intralamellar dissection). The intraoperative parameters evaluated were initial preparation time, dissection time, and total time. At each follow-up, visual acuity, refractive status, keratometry, and endothelial cell counts were also analyzed.

RESULTS

Initial preparation time, dissection time, and total time were significantly decreased with the use of an adjunct (p < 0.05) and were found to be least with the use of BSS. No difference in these time frames was noted between group I and group II. Corneal haze and incomplete air insufflation were seen in group I, and difficulty in injection of 2% HPMC and its incomplete spread were noted in group II. The mean spherical equivalent, astigmatism, endothelial cell counts, and visual acuity did not show any significant difference between any group.

CONCLUSION

Hydrodelamination with BSS is easy to perform and should be undertaken routinely to facilitate recipient intralamellar dissection.

Comparison of topical 0.3% ofloxacin with fortified tobramycin plus cefazolin in the treatment of bacterial keratitis

PURPOSE

Ofloxacin is a broad spectrum fluoroquinolone antibiotic with good ocular penetration. We compared ofloxacin 3% solution with a combination of fortified tobramycin sulphate and cefazolin sodium solutions in the treatment of culture-proven bacterial keratitis.

METHODS

Thirty eyes with culture-proven bacterial corneal ulcers were enrolled in a prospective randomised, controlled, double-masked study for comparison. The ofloxacin drop and saline were decanted into two identical-looking bottles to the tobramycin and cefazolin. The cases were randomly allocated into treatment with 0.3% ofloxacin solution or a combination of fortified antibiotics (1.5% tobramycin and 10% cefazolin solutions; control group) along with supportive cycloplegic, vitamins and anti-glaucoma therapy. Student's t-test was used to compare the results.

RESULTS

Staphylococcus aureus and coagulase-negative staphylococci were the two most common organisms isolated. Resolution of the ulcer was achieved in 93% and 87% of cases in the ofloxacin and control groups respectively. The mean time required for symptomatic relief was 7.8 +/- 1.54 days and for epithelial healing 15.0 +/- 3.86 days in ofloxacin group, compared with 8.33 +/- 1.54 days for symptomatic relief and 15.46 +/- 3.86 days for epithelial healing in the control group. Post-resolution best corrected visual acuity of 20/200 or better was achieved in all but one eye in both groups.

CONCLUSIONS

Ofloxacin and combined fortified tobramycin and cefazolin topical drops were comparable for treating cases of bacterial corneal ulcer. However, considering its easy availability and cost-effectiveness, monotherapy with ofloxacin is preferred over the combined fortified tobramycin and cefazolin therapy.

Risk factors for pediatric presumed microbial keratitis: a case-control study

PURPOSE

To evaluate risk factors for pediatric presumed microbial keratitis and to describe the clinical picture, microbiologic spectrum, treatment modalities, posttreatment sequelae, and visual outcome in cases of pediatric presumed microbial keratitis.

METHODS

A case-control study design was used to identify the risk factors associated with pediatric presumed microbial keratitis. Fifty cases of fresh corneal ulceration aged 12 years or younger were compared with 50 controls. The study variables included were age, gender, immunization status, nutritional status (weight for height), and socioeconomic status. The clinical presentation of the cases with corneal ulceration, microbiologic spectrum, and treatment modalities also were evaluated. All the cases were followed up for a minimum of 3 months, and the posttreatment sequelae and visual outcome were analyzed.

RESULTS

The mean (+/- standard deviation) age of children with corneal ulceration and controls was 4.8 (+/-3.8) years and 5.1 (+/-2.8) years, respectively. Incomplete immunization status (AOR [95% confidence interval (CI)], 1.34 [0.62-2.9]) and poor nutritional status [AOR (95% CI) 1.06 (0.68-1.6)] were not found to be the predictors of corneal ulceration. Lower socioeconomic status was significantly associated with the occurrence of corneal ulceration [AOR (95% CI) 1.52 (1.1-2.3)]. Corneal trauma (38%) and systemic illness (24%) were the most often associated predisposing factors. Seventy percent of the cases were culture positive. Staphylococcus (70%) species was the most frequently isolated, followed by Pseudomonas aeruginosa (10%). Fungi were isolated in five eyes. Postresolution visual acuity at 3 months could be recorded only in 31 eyes and a visual acuity of 6/18 or better was achieved in 22% of these cases.

CONCLUSION

Corneal ulceration in pediatric age group in India is associated with poverty.

Lateral tarsorrhaphy: is it preferable to patching?

PURPOSE

To evaluate the effectiveness of lateral tarsorrhaphy for the management of postkeratoplasty epithelial defects.

METHOD

Thirty-six patients with persistent postkeratoplasty epithelial defects that did not heal despite topical medical therapy for a period of 96 hours were treated with either a lateral tarsorrhaphy (18 patients) or with tight patching (18 patients). All patients were evaluated daily by slit-lamp examination until complete reepithelialization occurred.

RESULTS

The epithelial healing was significantly faster (7.61+/-0.91 days vs. 12.6+/-1.61 days, p<0.5) in the lateral tarsorrhaphy group. Further, the patients with lateral tarsorrhaphies were significantly more comfortable when compared with those of the patching group (p<0.05).

CONCLUSION

Lateral tarsorrhaphy provides quick symptomatic relief and faster corneal epithelial defect healing. Therefore, it may be of benefit in cases of postkeratoplasty persistent epithelial defects.

Oversized grafts in children

OBJECTIVE

To evaluate the efficacy of oversized corneal grafts in the pediatric age group.

DESIGN

Prospective, nonrandomized clinical trial.

PARTICIPANTS AND INTERVENTION

Forty pediatric patients with unilateral or bilateral corneal opacification of congenital or acquired origin underwent corneal grafting surgery over a period of 2 years using donor corneal buttons oversized by 1 mm.

MAIN OUTCOME MEASURES

The parameters evaluated were indications for keratoplasty, graft clarity, visual acuity, keratometry, spherical equivalent, anterior chamber depth, and complications.

RESULTS

Corneal ulceration was the most common cause of corneal opacification (25%), followed by trauma (20%) and sclerocornea (20%). At 1 year, clear grafts were achieved in 85% of the cohort. The average keratometry at the end of 1 year was 43.28 +/- 1.65 diopters (D) in the congenital opacity group and 43.04 +/- 2.20 D in the acquired group. The keratometric astigmatism was 3.60 +/- 2.60 D in the congenital group and 2.52 +/- 2.20 D in the acquired group. Oversized grafts provided an adequate anterior chamber depth of 2.20 +/- 0.612 mm in the congenital group and 2.36 +/- 0.302 mm in the acquired group. Visual acuity of 20/80 or better was recorded in only 30% of cases in the congenital group as opposed to 47% with acquired opacities. Nine cases had episodes of graft rejection.

CONCLUSION

Oversizing donor buttons by 1 mm provides adequate anterior chamber depth and increases the morphologic success of corneal grafting in children.

Lamellolamellar sclerokeratoplasty. Where do we stand today?

PURPOSE

To determine the efficacy of lamellar sclerokeratoplasty for patients with extensive corneal/corneoscleral lesions.

METHODS

One hundred and sixty-six eyes with extensive corneal/corneoscleral lesions of different aetiology who were poor candidates for conventional lamellar keratoplasty/penetrating keratoplasty were selected for lamellar sclerokeratoplasty.

RESULTS

Corneal clarity of 3+ or more was achieved in 62 eyes by a single procedure. In the remaining 104 eyes graft clarity was < 2+ due to post-surgical complications (n = 56) or remaining recipient deep opacity (n = 48).

CONCLUSIONS

Astigmatism, the bugbear of final visual achievement despite a clear graft, was not a frequent problem following lamellar sclerokeratoplasty. Similarly, a gain in visual acuity to 6/18 or more in 30% of eyes, cosmetic improvement in the majority of cases and prevention of recurrence of the original disease process in susceptible cases all point towards the safety and effectiveness of the procedure. Thus, lamellar sclerokeratoplasty should be considered as a management option for patients with extensive corneal/corneoscleral lesions.

Rhodotorula sp. infection in corneal interface following lamellar keratoplasty--a case report

PURPOSE

To report an unusual organism causing infection following lamellar keratoplasty.

METHOD

Case report.

RESULT

Both gram stain smear and culture from the interlamellar bed revealed Rhodotorula sp., a red yeast as a causative agent.

CONCLUSION

Rhodotorula sp. can cause corneal lamellar graft infection.

Deep lamellar keratoplasty versus penetrating keratoplasty for corneal lesions

PURPOSE

To compare the effectiveness of deep lamellar keratoplasty (DLK) with that of penetrating keratoplasty (PKP) in cases of corneal lesions not involving the endothelium.

METHODS

Forty-eight eyes with leukomatous corneal opacity (n = 33), keratoconus with apical scarring (n = 6), granular corneal dystrophy (n = 5), lattice corneal dystrophy (n = 2), and multiple corneal foreign bodies (n = 2) in an age group varying from 16 to 53 years underwent DLK (n = 24) and PKP (n = 24) by utilizing B and (B+ and A) grade M-K preserved donor tissue, respectively. The patients were followed up closely, and the graft clarity, visual achievement, astigmatism and endothelial cell count were evaluated at repeated occasions up to 1 year.

RESULTS

Astigmatism of <3 diopters (D) and > or = 5D was obtained in 19 eyes and one eye, respectively, after DLK at 6 months, whereas six eyes of the PKP group had astigmatism <3D, and 12 eyes had > or = 5D at the end of 6 months. The same at 1 year was observed in 20 and one eye in the DLK and eight and five eyes of the PKP group. Astigmatism of > or = 5D at the end of 6 months in both the groups showed highly significant changes (p < 0.001). Best corrected visual acuity of 6/18 or more was achieved in 18 and 12 eyes at 6 months after DLK and PKP, respectively, which were statistically highly significant (p < 0.001), whereas at 1 year, it was seen in 17 and 15 eyes of the DLK and PKP groups, respectively, which was nonsignificant. The mean endothelial cell count was 2,233.3+/-64.453 cells/mm2 and 2,219.6+/-102.48 cells/mm2 at 6 months and I year, respectively, after DLK, which was nonsignificant. The mean cell count of the donor eyes used for PKP was 2,191+/-52.164 cells/mm2, 1,902.8+/-70.346 cells/mm2 at 6 months, and 1,579.0+/-80.24 cells/mm2 at 1 year. All the values showed highly significant changes (p < 0.001). Further, the graft clarity of > or = 3+ was achieved in 20 and 18 eyes at 6 months postoperatively in the DLK and PKP groups, whereas the same was observed in 19 and 13 eyes of both the groups, respectively, at 1-year follow-up.

CONCLUSION

DLK is a promising procedure and should be practiced more frequently for corneal pathology not involving the endothelium.

Therapeutic sclerokeratoplasty versus therapeutic penetrating keratoplasty in refractory corneal ulcers

PURPOSE

To assess the efficacy of newer surgical technique of sclerokeratoplasty in cases of refractory corneal ulcers of the cornea and to compare it with therapeutic penetrating keratoplasty.

METHODS

A randomized, prospective clinical trial in 20 eyes with refractory corneal ulcers was undertaken. Ten eyes each underwent sclerokeratoplasty (group I) or therapeutic penetrating keratoplasty (group II). Infections were considered cured if there was no evidence of corneal infiltration for 1 month following keratoplasty. Postoperative complications, visual acuity (VA), keratometry and graft status were evaluated with both the procedures after a minimum follow up of 1 year.

RESULTS

Postoperative complications included epithelial defects, shallow anterior chamber, uveitis and secondary glaucoma, which were present following both procedures, with no significant difference in the frequency of complications between the two techniques (P < 005), Graft clarity and VA with both procedures were comparable. Significantly reduced astigmatism of < 1 D was seen in six eyes in group II in comparison with group I, where astigmatism of > 1.5 D was present in six eyes. Two eyes in group II developed re-infection, of which one was re-operated on, and the other developed endophthalmitis.

CONCLUSIONS

Sclerokeratoplasty is a useful alternative to therapeutic penetrating keratoplasty in cases of refractory corneal ulcers with optimum clinical and useful visual outcome.

Ruptured globe 10 years after radial keratotomy

PURPOSE

To report 3 cases (3 eyes) of globe rupture following blunt trauma 10 to 13 years after radial keratotomy.

METHODS

Cases of traumatic ruptured globe after radial keratotomy were reviewed from a tertiary eye care center. One eye underwent therapeutic penetrating keratoplasty, the second was treated with a bandage contact lens, and the third developed retinal detachment leading to phthisis bulbi.

RESULTS

Ruptured globes occurred through the keratotomy incision during activities of daily living (1 eye), assault (1 eye), and sports (1 eye). Two eyes regained a visual acuity of 20/30 or better; 1 eye was lost.

CONCLUSION

Traumatic rupture of the cornea can occur more than 10 years after radial keratotomy.

Sclerokeratoplasty versus penetrating keratoplasty in anterior staphyloma

BACKGROUND AND OBJECTIVE

To assess the efficacy of the newer surgical technique of sclerokeratoplasty in spherical anterior staphyloma of the cornea and to compare it with total penetrating keratoplasty.

PATIENTS AND METHODS

A randomized, prospective clinical trial in 20 eyes with acquired spherical anterior staphylomas was undertaken. Ten eyes each underwent sclerokeratoplasty (group 1) or total penetrating keratoplasty (group 2). The parameters evaluated were visual acuity, keratometry, graft status, and complications. Patients were observed for a minimum of 1 year.

RESULTS

Best spectacle-corrected visual acuity of 6/60 or better with astigmatism of less than 3 D was achieved in all but one patient in group 1 in contrast to 5 cases in group 2. Postoperative complications included epithelial defects, shallow anterior chamber, hyphema, and uveitis, which did not significantly vary between the 2 procedures. Secondary glaucoma was significant associated with group 2 as compared with group 1. At the end of 1 year, no significant difference in the graft clarity was present. Grafts were clear 3+ or more in 8 eyes in group 1 and in 5 eyes in group 2. Good cosmetic results were achieved in cases of sclerokeratoplasty due to the absence of corneal opacification and suture marks.

CONCLUSION

Sclerokeratoplasty is a useful alternative to total penetrating keratoplasty in cases of acquired spherical anterior staphylomas of the cornea with good anatomic and useful visual outcome.

Post-penetrating keratoplasty glaucoma: risk factors, management and visual outcome

PURPOSE

To evaluate the incidence, associated risk factors, graft status and treatment modalities in patients with post-penetrating keratoplasty glaucoma.

METHODS

A retrospective analysis of 747 consecutive penetrating keratoplasties was undertaken at a tertiary eye care centre. The frequency of post-penetrating keratoplasty glaucoma was determined and correlated with the pre-operative corneal diagnosis, lens status and associated surgeries performed during penetrating keratoplasty. The response to antiglaucoma therapy (i.e. medical, surgical or cyclo-destructive procedures) and graft outcome was also evaluated.

RESULTS

The incidence of post-penetrating keratoplasty glaucoma was 10.6% (79/747). Pre-operative corneal diagnosis of adherent leucomas was significantly associated with the development of postoperative glaucoma. Post-penetrating keratoplasty glaucoma was significantly higher in aphakes (odds ratio (OR) 6.6; confidence interval (CI) 3.81-11.69) compared with phakic or pseudophakic eyes. Associated vitrectomy (OR 2.32; CI 1.16-4.73) and anterior segment reconstruction (OR 3.31; CI 1.43-7.72) were other high-risk factors. Most patients responded to medical therapy (41/79; 51.9%), whereas filtering surgery and cyclo-destructive procedures were performed in 29.1 (23/79) and 19% (15/79) of eyes, respectively. Despite clear grafts in 39 eyes (49.4%), visual acuity of 6/18 or better was achieved in 15 eyes (18.9%).

CONCLUSIONS

A high incidence of post-penetrating keratoplasty glaucoma occurs in eyes with adherent leucomas. Anterior vitrectomy and associated surgeries further accentuate the risk Anti-glaucoma therapy may not achieve optimum visual outcome, despite a clear graft.

Corneal infection after radial keratotomy

PURPOSE

To evaluate nine eyes that developed corneal infection after radial keratotomy (RK) and their subsequent management.

SETTING

Dr. Rajendra Prasad Centre for Ophthalmic Sciences, New Delhi, India.

METHOD

The parameters evaluated were interval between RK and development of the ulcer, number of keratotomy incisions, nature of surgery (primary or secondary), status at presentation, and best corrected visual acuity (BCVA). Corneal scrapings were taken from all eyes for microbiological evaluation. Initial therapy was based on clinical impression and subsequent therapy, on the microbiological report.

RESULTS

Staphylococcus species were the most frequently isolated bacteria followed by Pseudomonas aeruginosa. Two eyes had fungal growth, and no organisms were isolated from one. All but one eye responded to medical therapy; healing took 23 to 26 days. Therapeutic penetrating keratoplasty (PKP) was done in one eye. Presenting BCVA of hand movement to 6/36 improved to hand movement to 6/18 after the ulcer healed. Final BCVA was 6/36 to 6/9 after lamellar keratoplasty or PKP or with contact lens of spectacle correction.

CONCLUSION

Our study shows that corneal infection is a potential complication of RK. Therefore, persistent postoperative irritation should be carefully observed to ensure early diagnosis and prompt therapy.

Randomized trial of intraoperative mitomycin C in surgery for pterygium

PURPOSE

To report the efficacy and safety of intraoperative application of mitomycin C in surgery for pterygium.

METHODS

In a prospective randomized and double-blind study done within a span of 2.5 years in 50 eyes (50 patients) with primary progressive pterygium, mitomycin C in a concentration of 0.02 mg/ml soaked in a sterile 5 x 5-mm sponge was applied over the bare sclera intraoperatively as an adjuvant therapy in 25 eyes after pterygium excision. These cases were compared with another 25 similar eyes that underwent the same procedure but in which gentamicin solution 0.3% was used instead of mitomycin C solution.

RESULTS

Three eyes (12%) in the mitomycin C group showed recurrence within 7 months of surgery compared with eight eyes (32%) of the gentamicin control group within 3 to 5 months. Mild side effects, such as pain, photophobia, and delayed wound healing, were observed within the first 1 to 2 weeks postoperative in both groups. In the mitomycin C-treated group, corneal changes in the form of superficial punctate keratitis (three eyes) and limbal avascularity (two eyes) subsided within 2 weeks postoperatively. Follow-up time for these cases ranged from 18 to 21 months.

CONCLUSIONS

A diluted solution of mitomycin C, 0.02 mg/ml, with an accurate size of sterile sponge applied to bare sclera after primary pterygium excision decreases the rate of recurrence to a greater extent than does gentamicin solution and is not associated with severe complications.

Decreased nitric-oxide synthase activity causes impaired endothelium-dependent relaxation in the postischemic heart

Endothelial nitric-oxide synthase (eNOS) is an important regulator of endothelial function and vascular tone in biological tissues. While endothelial dysfunction occurs following ischemia and has been attributed to altered NO. formation, the biochemical basis for this dysfunction is unknown. Therefore, studies were performed to determine the effects of myocardial ischemia and reperfusion on eNOS in isolated rat hearts subjected to periods of global ischemia or ischemia followed by reperfusion. eNOS activity was assayed by L-[14C]arginine to L-[14C]citrulline conversion and alterations in the amount and distribution of eNOS determined by Western blotting and immunohistochemistry. While activity was preserved after 30 min of ischemia with a value of 1.1 +/- 0.1 pmol x min-1 x mg of protein-1, it decreased by 77% after 60 min and became nearly undetectable after 120 min. Reperfusion resulted in only a partial restoration of activity. The decline in activity with ischemia was due, in part, to a loss of eNOS protein. Hemodynamic studies showed that the onset of impaired vascular reactivity paralleled the loss of functional eNOS. Subjecting isolated eNOS to conditions of acidosis, which occur during ischemia, followed by restoration of pH as occurs on reperfusion, caused a combination of reversible and irreversible loss of activity similar to that seen in ischemic and reperfused hearts. Thus, loss of endothelial function following ischemia is paralleled by a loss of eNOS activity due to a combination of pH-dependent denaturation and proteolysis.

Mycotic keratitis in children: epidemiologic and microbiologic evaluation

PURPOSE

To evaluate the demographic features, clinical profile, and laboratory diagnosis in cases of mycotic keratitis in children.

METHODS

We retrospectively analyzed 211 cases of mycotic keratitis in children younger than 16 years over a 5-year period in a tertiary eye center. Culture-proven cases of fungal keratitis were reviewed.

RESULTS

Trauma was the most common predisposing factor (55.3%), followed by associated systemic illness (11.2%), previous ocular surgery (9.8%), and others. Corneal injury contaminated with vegetable matter was responsible for 60.5% of traumatic cases. Aspergillus species were the most frequent isolates (39.5%). Others included Fusarium (10.7%), Alternaria (10.2%), Curvularia (7.4%), and Penicillium (7%). A seasonal variation in the incidence of mycotic keratitis revealed a peak incidence in the months of September and October. One hundred sixty-two children (76.7%) cooperated for examination and scraping under topical anesthesia with or without sedation. General anesthesia for scraping was required in 49 (23%) of 211 children for corneal scraping. Gram stains of corneal scraping were positive for hyphal elements in 54.5% of cases, and potassium hydroxide wet-mount preparation was positive in 90.2% of cases.

CONCLUSIONS

This study highlights important risk factors and organisms responsible for mycotic keratitis in children.