To the Editor:
We thank Dr Zimmerman for his response to the Wilderness Medical Society Practice Guidelines for Treatment of Eye Injuries and Illnesses in the Wilderness. We appreciate the thoughtful critique regarding both the American College of Chest Physicians (ACCP) classification system and the specific treatments of various eye conditions.
All grading systems have potential limitations. Wilderness medicine topics, in general, have limited and anecdotal evidence. Many of the recommendations given in this practice guideline are graded 1C, which indicates a “strong recommendation” with “low/very low quality evidence.” This recommendation encompasses case series, observational studies, and the like, which is appropriate for the level of evidence that we reviewed.
Some definitive treatments in this guideline are graded 1A, and although it may not be possible to perform all of these in the wilderness setting, they are included to educate all responders to the standard, evidenced-based treatment for the given condition, and to stress, particularly, that if not available in the wilderness, then emergent evacuation must ensue.
Central Retinal Vein Occlusion
It is true that the data to support any particular treatment for central retinal vein occlusion (CRVO) are lacking. To quote Yanoff and Duker's ophthalmology text: “No known treatment reverses the pathology seen in CRVO. Aspirin; systemic anticoagulation with coumadin, heparin, and alteplase; local anticoagulation with intravitreal alteplase; corticosteroids; anti-inflammatory agents; isovolemic hemodilution; plasmapheresis; and optic nerve sheath decompression all have been advocated but without definitive proof of efficacy.” 1 Topical steroids have been suggested for emergency treatment of CRVO. 2 Because there are minimal data supporting any particular treatment and because there are few downsides to topical steroids, it was determined to be a feasible option for wilderness treatment. We agree that this is in the realm of expert opinion and, therefore, may be better rated as a 2C recommendation.
Conjunctivitis
The 1A recommendation should have only been applied to the recommendation for topical antibiotics. The Cochrane Review that is referenced showed that “… the use of antibiotics is associated with significantly improved rates of clinical and microbiological remission.” 3 The data supporting systemic antibiotics are not as strong and should not have been listed as a recommendation.
Although trachoma may be encountered among a local population abroad, it is rarely encountered during a wilderness excursion, and discussion of global eye diseases was beyond the scope of these guidelines.
Corneal Abrasion
It is correct that the review cited did not specifically address cycloplegics used without nonsteroidal antiinflammatory drugs, as the study evaluated patching versus other treatments and was not intended to specifically look at cycloplegics versus nonsteroidal antiinflammatory drugs. This was, however, the strongest available evidence for treatment of corneal abrasion and, therefore, is the treatment on which we based our recommendation. The study by Brahma et al 4 does note that topical nonsteroidal antiinflammatory drugs alone were a superior treatment; however, this isolated randomized controlled trial has not yet been reproduced, and we look forward to further research into this question.
Corneal Frostbite
Although the ACCP grading system might not be ideal for all wilderness medicine evidence as discussed below, we feel that based on that system, the 1C recommendation is most appropriate for corneal frostbite. The evidence is “low quality or very low quality,” yet the benefits clearly outweigh risks and burdens.
Finally, the ACCP grading system was chosen to comply with the international GRADE (Grading of Recommendations Assessment Development and Evaluation) 5 Working Group guidelines, and it was used to evaluate the evidence for the first set of Wilderness Medical Society (WMS) practice guidelines regarding altitude illness. Altitude illness has a large body of high quality evidence for which the ACCP system worked well. As you have mentioned, for topics with lower quality evidence, the ACCP may not be the ideal grading system, and the WMS Practice Guidelines Committee will be tasked with deciding whether to replace it in future editions of the WMS Practice Guidelines.