EyeWorld China September 2019 Issue

Contoura TM is a bi-modal treatment shaving off peaks and steeping the flatter areas of cornea providing optimal corneal curvature. It is static, reproducible, provides better peripheral data, and is not affected by age, pupil size and corneal opacity. Table 1: Pre-requisites for Contoura TM Vision • High quality topography is essential • Good correlation between topographic and refractive astigmatism is necessary • Ablation profiles of T-CAT and wave front optimized should be compared • Use of same target Q value as pre-operation value (0 to -1) is essential • Proper patient alignment under the laser needs to be ensured Managing Topography-guided Treatments in the Clinics Dr. Ryu Ik Hee 2 Clinical Science Behind Contoura TM Dr. Dandapani Ramamurthy Prof. Zhang Fengju Beijing Tongren Eye Center, Beijing Tongren Hospital of Capital Medical University, China Dr.DandapaniRamamurthy Chairman, The Eye Foundation, India Dr. Arthur Cummings Consultant Eye Surgeon, Wellington Eye Clinic Consultant Ophthalmologist and Head of the Department of Ophthalmology Beacon Hospital, Ireland Dr. Ryu Ik Hee Chief Director, B&VIIT Eye Center, Seoul, South Korea said Dr. Dandapani Ramamurthy. Dr. Ramamurthy shared his personal views and recommendations on pre-requisites to achieve optimal refractive and visual outcome with Contoura TM Vision (Table 1). The Contoura TM Vision is a topography-guided treatment on eyes that utilizes a placido ring based topographical system (Topolyzer VARIO or Allegro Topolyzer). The patient’s eye is imaged and analyzed using 22 rings and 22,000 unique elevation points on the cornea. This data is sent to the surgical planning computer to create an individualized ablation profile, following which a Wavelight ® EX500 or Excimer Laser automatically adjusts laser pulse placement to match the topography-guided treatment. Contoura TM Vision is performed either on EX500 or EYE-Q in conjunction with Topolyzer VARIO with the help of T-CAT software. The software calculates treatment plan combining manifest refraction data and corneal irregular shapedata fromtopographer. A minimum of 4 examinations are imported and the system calculates the median (corneal radius and asphericity), following which the HOAs are calculated, and finally the sphere and astigmatism estimation by the surgeon is added. “During Contoura TM , the elevated parts of the cornea are depressed, and the surrounding areas around the depressed parts are elevated. This bi- modal treatment results in reduced consumption of tissue and more regularization of the cornea” Table 2: Consideration for Keratoconus using Wavelight Oculyzer TM 1. Anterior float criteria • Normal values: < +12 µm (or 10 µm) • Suspicious: from 12 µm to 15 µm • KCN : > 15 µm 2. Posterior float criteria • Normal values: < + 17 µm • Suspicious: from 18 µm to 20 µm • KCN: > 20 µm With an experience of more than 1000 procedures using the Contoura TM Vision, Dr. Ryu Ik Hee shared his insights and provided valuable guidance on managing topography-guided treatments in clinical practice. Topography-guided Contoura TM Vision is ideal for patients who need customized procedures, including those with irregular topography findings (superior or inferior steepening), and those with astigmatism by manifest refraction of >2D or when index of height decentralization (IHD) > 0.01, which is the most significant value during screening. Abnormal topo map as seen from the Wavelight ® Oculyzer TM , should be considered suspicious for keratoconus (Table 2). “I consider anterior float criteria >15 µm and posterior float criteria >20 µm suspicious for keratoconus (KCN) eliminating laser refractive surgery”, explained Dr. Ryu.