EyeWorld China September 2019 Issue

Outcomes of the New Combined Treatments for Keratoconus Dr. Aanchal Gupta The triple procedure has shown promising results in patients with keratoconus. Although cross-linking is excellent in terms of halting progression, there are un-answered questions on howmuch cross-linking is sufficient and whether combined modalities are safe and effective over longer duration of time. A long-term follow-up of a larger population study is required to validate the current findings. 6 Topography-Guided Treatment for Irregular Corneas Dr. Arthur Cheng TOPOGRAPHY-GUIDED TREATMENT FOR DIFFICULT CASES Topography guided PRK is becoming increasing popular in the treatment of irregular corneas. It has shown improvement in better astigmatic correction, best- corrected visual acuity (BCVA), and enhancement of quality of vision. Table 3 : Procedure of Topography guided PRK followed by CXL Step 1 PTK to remove uneven epithelium on corneal surface Step 2 • Topography guided PRK to reduce irregularities of the corneal surface • Asphericity adjustment • Myopic compensation • Astigmatic compensation • Limited ablation depth to aim for stromal thickness of > 400 μm Step 3 Crosslinking Step 4 Application of mitomycin C to prevent scarring and reduce haze Corneal ectasia, keratoconus, scarring, trauma and previous surgical procedures are some common causes of irregular cornea, leading to significant visual disabilities. “Topography-guided treatment that combines myopic and hyperopic ablations has demonstrated successful outcomes in patients with irregular corneas,” said Dr. Arthur Cheng. Keratoconus is commonly seen in the clinics. The treatment options for keratoconus include corneal collagen crosslinking (CXL), intraocular stromal ring and topography guided PRK plus crosslinking. Though corneal collagen crosslinking is effective in halting disease progression, it is not effective in correcting abnormal shape. Intraocular stromal ring has an unpredictable outcome and is not applicable to central cone. On the other hand, topography guided PRK followed by CXL has shown promising results, and better outcomes. The steps involved in performing Topography-guided PRK followed by CXL is explained in Table 3. “The idea of topography guided PRK is to reverse the disease progression in patients with irregular corneas; that is to reverse the myopia, reverse astigmatic change and reverse coning.” added Dr Cheng. Another important consideration in topography guided trans-epithelial PRK is the need for appropriateadjustmentof spherical equivalentafter correction of astigmatism. Spherical compensation can reduce the cone curvature and flatten the central cornea. “The extent of compensation depends on the steepest area and the underlying refractive error,” explained Dr. Cheng. Young patients with progressive keratoconus, who are not satisfied with rigid contact lenses and a high degree of refractive error, are common in everyday practice. These cases are often complicated with very poor uncorrected and best-corrected visual acuity. Dr. Aanchal Gupta’s approach in these patients is keraring implantation followed by a topography- guided PRK (TG PRK) after 3 months. “The waiting time of 3 months is essential because there is a huge amount of regularization needed for such severe corneas,” explained Dr. Gupta. “If the best-corrected visual acuity post keraring implantation is poor, then an ICL will not be suitable because patient still has a very irregular cornea.” Dr. Gupta’s unpublished data on triple procedure including TG PRK with CXL post keraring implantation in keratoconus patients has been encouraging. The TG PRK was done using the topography-guided