The cataract surgery planning process  begins with accurate measurements. The most critical in calculating correct IOL power is axial length followed by K readings. Some patients will achieve better outcomes with intervention to improve the measurement accuracy. Here are six conditions that may benefit from additional care before the surgical consult.

SIX DIAGNOSES REQUIRING MORE INTERVENTION

1. Dry Eye—Dry eye syndrome is the most common cause of inaccurate K readings. The clinical examination is often normal early in the condition and is well underway by the time we can observe epithelial disruption and staining. If a patient has subjective visual complaints related to cataracts and has evidence of dry eye syndrome, we encourage aggressive dry eye management before cataract surgery evaluation.

2. Fuchs’ Dystrophy—Patients with guttata in the absence of corneal edema do not have true Fuchs’ dystrophy, but they do require education about the increased risk of corneal edema and prolonged healing time following cataract extraction. When guttata is present, we take additional precautions during surgery by using anterior chamber viscoelastics to condition and protect the corneal endothelium.

In patients with guttata and abnormally thick corneal pachymetry or findings such as stromal folds, consider beginning hypertonic solutions pre-operatively and continue them throughout the surgical healing process. Sodium chloride 5% QID (brand name or a more affordable generic) has been shown to improve visual acuity and corneal edema following cataract extraction. For recalcitrant edema that is not responding to steroids and hypertonic ophthalmic solution, it may be beneficial to add the topical rho-kinase inhibitor netarsudil QHS*. In extreme cases, patients may benefit from combined cataract surgery and endothelial keratoplasty.

3. Pterygium—While often small and asymptomatic, pterygium progression can be slowed and sometimes prevented. Patients should be educated about the importance of UV and wind protection, as well as the benefits of frequent lubrication. If the pterygium is chronically inflamed, impinging on the visual axis, or causing irregular astigmatism, it may be time for surgical intervention.

4. Visually significant EBMD

Epithelial basement membrane dystrophy (EBMD) is the most common corneal dystrophy and typically appears in a map-dot-fingerprint pattern. Mild cases benefit from over-the-counter artificial tears to improve comfort and visual stability. But once EBMD becomes moderate or severe, further intervention is needed.

Features of progression include lesions near or within the visual axis or episodes of recurrent corneal erosion. In both cases, superficial keratectomy or a more invasive phototherapeutic keratectomy (PTK)  should be considered before cataract extraction.

5. Salzmann nodular degeneration

Salzmann nodular degeneration can have a myriad of clinical presentations. Most commonly, small gray-white to bluish nodules are observed in the peripheral cornea. They usually have adjacent vascularization and can coalesce into one large nodule. These nodules are common superiorly and are sometimes missed when obstructed by the superior eyelid.











Salzmann nodular degeneration is associated with lid margin disease, dry eye syndrome, and soft contact lens wear. It may even have an autoimmune component. Cataract patients who have developed irregular corneal astigmatism—especially those interested in premium IOLs—will benefit from mechanical debridement or PTK before cataract extraction.

6. Progressive post-refractive corneal ectasia

Accurate measurements before cataract extraction are essential in patients with a history of refractive surgery. Radial keratometry, LASIK, and PRK all change the cornea from its natural shape and thereby decrease the accuracy of IOL calculations. Whereas keratoconus often begins at puberty and stabilizes by the fifth decade of life, post-refractive ectasia can be progressive at any age.

There is no consensus as to how to determine progressive corneal ectasia. Most providers use a combination of maximum keratometry (Kmax), pachymetry, spherocylindrical refraction, and best-corrected vision. The Belin/Ambrosio Enhanced Ectasia Display (BAD) on the Pentacam analyzes anterior and posterior corneal surface elevation with pachymetric data to determine if ectasia is present. It can also help confirm progressive disease.

CONCLUSION

When preparing patients for cataract extraction, our best tools are counseling and education. In addition, aggressive management of these corneal conditions ahead of cataract surgery improves the accuracy of keratometry measurements and increases the likelihood of patients achieving the best outcome.