AAO Preferred Practice Pattern 2018 for Corneal Edema and Op
The American Academy of Ophthalmology (AAO) has updated its 2013 Preferred Practice Pattern (PPP) guidelines for Corneal Edema and Opacification.

Corneal edema is the retention of excess fluid within one or multiple layers of the cornea whereas corneal opacification results from the presence of additional material (e.g., fluid, scar tissue, inflammatory debris, metabolic byproducts) within one or multiple layers of the cornea that is associated with loss of corneal clarity.

The reduction or elimination of corneal edema or opacification is indicated when it is associated with functional visual loss or discomfort. Chronic epithelial breakdown associated with underlying stromal or endothelial dysfunction may necessitate intervention to stabilize the ocular surface and prevent further complications. Less commonly, cosmesis is an indication for treatment.

Highlighted findings and recommendations for care include the following:-

• The impact of corneal edema on activities of daily living―particularly those influenced by ambient light levels at home, work, and during leisure activities―is often underappreciated. Standard measurement of visual acuity does not give a true representation of the patient’s functional vision.

• Reduced vision in cases of corneal opacification is more often related to corneal surface irregularity than to the opacity itself. A refraction over a rigid gas-permeable (RGP) contact lens can be very helpful in determining if visual loss is due to a corneal surface irregularity.

• Endothelial function is best evaluated by slit-lamp biomicroscopy examination and may be supported by changes in corneal thickness noted on serial pachymetric measurements performed at the same time of day. Specular microscopy is not a direct measure of endothelial function or functional reserve. When diffuse endothelial guttae are present on slit-lamp biomicroscopy examination, specular microscopy rarely provides any valuable information because it is difficult to image the endothelial cells.

• Corneal pachymetry, measured in the morning, is a helpful indicator of the ability of the endothelium to regulate corneal hydration appropriately. Corneas that are abnormally thick in the morning hours may be less able to tolerate proposed intraocular surgery. Indiscriminate use of topical antibiotics or corticosteroids should be avoided. Viral conjunctivitis will not respond to anti-bacterial agents, and mild bacterial conjunctivitis is likely to be self-limited. No evidence exists demonstrating the superiority of any topical antibiotic agent.

• If the cataract surgeon or cornea specialist thinks that decompensation, if not imminent, is likely to occur in the near future, a discussion about modifying the intraocular lens (IOL) power calculation is worthwhile to adjust for changes induced by endothelial keratoplasty (specifically a hyperopic shift due to Descemet stripping automated endothelial keratoplasty [DSAEK] and less so with Descemet membrane endothelial keratoplasty [DMEK]). A full discussion of the added risks of subsequent corneal decompensation is very important in this group of patients and helps to shape their expectations with respect to their condition and the surgery.

• Endothelial keratoplasty has supplanted penetrating keratoplasty as the procedure of choice in cases of endothelial failure in the absence of corneal scarring because patients achieve more rapid visual rehabilitation and reduction in rejection of the transplanted tissue.

About AAO
The American Academy of Ophthalmology (Academy) is a professional medical association of ophthalmologists. It is headquartered in San Francisco, California. The Academy's stated mission is "to protect sight and empower lives by serving as an advocate for patients and the public, leading ophthalmic education, and advancing the profession of ophthalmology."

Note: This list is a brief compilation of some of the key recommendations included in the Guidelines and is not exhaustive and does not constitute medical advice. Kindly refer to the original publication here: https://pxmd.co/IL3nL
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