The corneal surface is the eye's first refracting surface. As such, we cannot overemphasize the importance of ocular surface health in ensuring optimal postsurgical outcomes in standalone refractive surgery as well refractive cataract surgery.
All presurgical measurements, planning and testing require a good corneal “foundation” to be accurate.
A recent American Society of Cataract and Refractive Surgery (ASCRS) practice survey found that although more than 90% of respondents felt even mild-to-moderate dry eye had an impact on patients’ satisfaction postoperatively, less than 10% were using modern techniques for identifying and treating ocular surface disease (OSD) in their routine preoperative assessments. To address this rather large educational gap, the ASCRS Cornea Clinical Committee (CCC) developed a new practical diagnostic OSD algorithm (Starr et al.) to aid surgeons in efficiently diagnosing and treating visually significant disease before surgery.
Do we need another algorithm?
How is this algorithm different from the others from the Tear Film and Ocular Surface Society Dry Eye Workshop (DEWS) II or the American Academy of Ophthalmology Preferred Practice Patterns or the Cornea, External Disease and Refractive Society and the American Society of Progressive Enterprising Surgeons? It is specifically designed for preoperative patients. This population has unique considerations, including their exacting expectations with regard to refractive outcomes and their potential reluctance to report symptoms of OSD. There is also an overall lack of correlation between signs and symptoms in older patients in particular. Therefore, this algorithm works even in the absence of patient complaints.
The decision to delay surgery for necessary OSD treatment is serious. However, not all subtypes of OSD necessarily require taking such steps, so the new algorithm introduces the concept of two presurgical OSD categories: non-visually significant OSD and visually significant OSD (VS-OSD). VS-OSD is treated aggressively to minimize the surgery delay.
Points of emphasis
The ASCRS team created a new questionnaire that kicks off the algorithm process. The ASCRS-modified Preoperative OSD Standardized Patient Evaluation of Eye Dryness (SPEED) II is designed specifically for preoperative refractive surgery patients. The added questions help screen relevant subtypes of OSD that consider the interplay between premium procedures, refractive IOL results and out-of-pocket expenses.
The algorithm suggests two initial screening tests: tear osmolarity and inflammation (MMP-9). These two point-of-care tear tests are sensitive and specific for diagnosing dry eye disease, with tear hyperosmolarity being understood as central to the modern definition of DED (Lemp et al., Sambursky et al., Cornea). The TearLab Osmolarity System (TearLab Corp.) and other osmometers can be easily integrated into a routine workflow. A measure of inflammation, MMP-9 plays a key role in the breakdown of the ocular surface and can also be quantified with the sensitive and specific InflammaDry test (Quidel Corp.) (Sambursky et al., JAMA Ophthalmol, Sullivan et al.).
If any one of the three components evaluated to this point is abnormal, it means the presurgical patient is at risk for OSD, according to the algorithm, and further diagnostic testing should be conducted to identify subtypes of disease. Treatment is recommended at DEWS Stage 2.
Look, lift, pull push
In terms of the physical examination, the CCC introduced a mnemonic, calling the quick-focused ocular surface examination “look, lift, pull, push” (LLPP) to confirm the subtype, severity and visual significance of any present OSD.
According to the report, look at the blink quality and quantity, examine the eyelids for malposition and visually assess the tear meniscus height. Look for signs of anterior and posterior blepharitis. Look at the interpalpebral ocular surface for signs of conjunctival injection, and look at the interpalpebral cornea for any surface abnormality.
Lift up and pull out the upper eyelid, primarily to rule out superior epithelial basement membrane disease and to identify eyelid laxity and floppy eyelid syndrome.
Push on the lower lid margin to express the meibomian glands and assess the quality, quantity, and flow of the meibum. Gland expression can be particularly helpful in identifying patients with nonobvious meibomian gland dysfunction
As it turns out, yes, we did need another algorithm. This one!
Craig JP, et al. Ocul Surf. 2017;doi:10.1016/j.jtos.2017.08.003.
Lemp MA, et al. Am J Ophthalmol. 2011;doi:10.1016/j.ajo.2010.10.032.
Sambursky R, et al. JAMA Ophthalmol. 2013;doi:10.1001/jamaophthalmol.2013.561.
Sambursky R, et al. Cornea. 2014;doi:10.1097/ICO.0000000000000175.
Sullivan BD, et al. Invest Ophthalmol Vis Sci. 2010;doi:10.1167/iovs.10-5390.
Starr CE, et al. J Cataract Refract Surg. 2019;doi:10.1016/j.jcrs.2019.03.023.
The definition and classification of dry eye disease: report of the Definition and Classification Subcommittee of the International Dry Eye WorkShop. Ocul Surf. 2007;5:75–92.