Argon Laser Treatments Can Preserve Vision in Children With Parasitic Infection

Argon laser photocoagulation is a safe, effective novel treatment for presumed trematode-induced granulomatous anterior uveitis with pearl-like nodules in pediatric populations, according to research results published in the British Journal of Ophthalmology. 

In rural Egypt, presumed trematode-induced granulomatous anterior uveitis is common in children, and is associated with swimming or bathing in the Nile River and freshwater canals. Typical conservative treatment options include topical steroids; cycloplegic, trans-septal steroids; systemic steroids and antiparasitic administration; limbal cryotherapy; and surgical excision; however, complications from these conservative treatments are common. 

In a nonrandomized controlled clinical trial, researchers evaluated the safety and efficacy of argon laser photocoagulation — developed in 1964 — compared with usual medical treatment for this condition. 

Between May and October 2020, the investigators recruited 48 children with active presumed trematode-induced granulomatous anterior uveitis from a single academic center in Egypt. Children included in the study had 1 or 2 pearl-like masses in the anterior chamber (<3 mm), flare and cells ≥+1, and visual acuity >6/60 in the affected eye. 

Children were divided into 2 groups based on parental consent: parents in the first group consented to surgical intervention in the form of 1 session of argon laser therapy (23 eyes), while parents in the second group refused to allow their children to undergo the argon laser treatment. 

Patients in group A received topical anesthesia and underwent 1 session of argon laser photocoagulation applied directly to the anterior chamber lesions. Spot size was 100 to 200 µm, duration was for 0.2 to 0.4 seconds; power was 250 to 400 mJ; and shots were 10 to 25, depending on lesion response. 

Patients received topical steroids and cycloplegics 3 days before the treatment session. Postoperatively, topical eyedrops were administered, including gatifloxacin 0.3% given 5 times daily for 1 week, prednisolone acetate 1% given 5 times daily with a gradual taper for >4 weeks, cyclopentolate hydrochloride 3 times daily for 3 days, and brimonidine 2 times daily for 1 week. 

Patients in group B underwent a conservative treatment regimen including trans-septal triamcinolone acetonide (40 mg/mL) injection under topical anesthesia, topical prednisolone acetate 1% eye drops 5 times daily with a gradual taper for >4 weeks, cyclopentolate hydrochloride 1% given 3 times daily for 2 weeks, and topical gatifloxacin 0.3% eye drops 5 times daily for 1 week. 

All patients were evaluated at 1 day, 2 weeks, 1 month, and 3 months, with measurements of visual acuity, intraocular pressure (IOP), grade of AC reaction, and presence of AC granulomas. 

Forty-eight eyes from the 48 children in the study cohort were included. There were no between-group differences in terms of baseline demographic or ocular findings. Mean age in group A was 11.17±1.72 years; mean age in group B was 11.4=1.89 years. Most children were boys with a history of swimming or bathing in the Nile River. 

Preoperative best-corrected visual acuity (BCVA) in group A was 0.52±0.12 logMAR; postoperative values were 0.22±0.1, 0.11±0.08, and 0.06±0.08 at 2 weeks, 1 month, and 3 months, respectively. Cases with +2 and +3 anterior chamber cells decreased from 21 preoperatively to 0 at month 3 follow-up. Nodules in the anterior chamber resolved in 95.65% of patients, with anterior chamber reaction within 2 to 4 weeks of treatment; response was maintained throughout the follow-up period. 

Researchers did not detect any serious complications either during or after the argon laser treatment. Only 1 patient demonstrated an IOP increase to 27 mmHg on the day after the session; the investigators managed this with a topical beta-blocker plus brimonidine. One patient experienced hyphema, which resolved immediately following therapy. 

Only 1 patient was resistant to photocoagulation, demonstrating minimal initial shrinkage and recurrence within 3 months. 

In group B, preoperative mean BCVA was 0.53±12 logMAR; postoperative values were 0.24±0.01 at 2 weeks, 0.1±0.07 at 1 month, and 0.16±0.17 at 3 months. Cases with +2 and +3 anterior chamber cells decreased from 23 preoperatively to 0 at 3 months, but the number of cases with +0.5 and +1 anterior chamber cells increased from 2 to 12 during the study period. Nodules resolved in 92% of patients within 1 month of the initiation of medical treatment; however, 9 cases demonstrated recurrence at the end of the 3-month follow-up period and the percentage of resolved nodules decreased to 56%. 

No complications were reported following trans-septal triamcinolone injection, and no cases of cataract or steroid-induced glaucoma were detected. 

The primary study limitation was the inclusion only of mild or moderate cases through the exclusion of patients with nodules larger than 3 mm and a “marked drop” in visual acuity. 

“To the best of our knowledge, this study was the first to test the use of argon laser photocoagulation for the treatment of patients with [presumed trematode-induced granulomatous anterior uveitis],” according to the researchers. “The technique is simple, cheap, noninvasive, and widely available in developing countries.”

“While the results are encouraging, future studies with larger samples and longer follow-up durations are needed to confirm our findings.” 

Reference

Alsmman AH, Abdalla A, Ezzeldawla M, Mossa EAM, Abozaid M. Argon laser photocoagulation for treatment of presumed trematode-induced granulomatous anterior uveitis in children. Br J Ophthalmol. Published online June 18, 2021. doi:10.1136/bjophthalmol-2021-318796