EyeWorld Asia-Pacific March 2016 Issue

43 EWAP Cataract/IOL March 2016 Views from Asia-Pacific Pannet PANGPUTHIPONG, MD Deputy Director General, Department of Medical Services, Ministry of Public Health Nonthaburi Province, Thailand pannetp@hotmail.com W hen making a clear corneal incision, I consider the following key factors: 1. Instruments: I prefer a steel blade because of cost-effectiveness, controllability, and ease of care. 2. Location: Always temporal. Selecting a superior or obliquelocation to correct preexisting astigmatism may end up with a refractive surprise especially with a larger incision (2.75 mm) due to unpredictable lid pressure. A smaller incision (sizes of 2.2–2.4 mm) induces less astigmatism but still causes less predictable surgically induced astigmatism (SIA) at superior or oblique positions. Temporal incisions induce the least astigmatism. 3. Size: For most uncomplicated cases, I prefer 2.4 mm because it does not require any special instruments, i.e., standard capsulorhexis forceps can be used. This size also produces acceptable SIA. 1.8–2.2 mm incisions require special capsulorhexis forceps and may also be more prone to wound leakage due to wound burnor stretching. In complicated cataracts such as a hard cataract, I prefer 2.75 mm incision. 4. Construction: Starting just anterior to the vascular arcade, entering corneal stroma with blade angle of 30 degree to the sclera. As the tip of the blade enters the anterior chamber, the blade angle is then parallel with the iris. With this technique, the wound length will be 1.5–2.0 mm. (To understand this, imagine a triangle with base of 1 mm and 30 degree apex, then sin 30° = 1/2). I prefer a corneal tunnel length of 1.5–2.0 mm. 5. Sealing: I prefer to seal every corneal incision with stromal hydration in the middle at the roof of the incision. This technique seals most of my cases including those with wound burn. Editors’ note: Dr. Pangputhipong declared no relevant financial interests. Abhay R. Vasavada, MS, FRCS (England) Raghudeep Eye Hospital Gurukul Road, Ahmedabad, India. icirc@abhayvasavada.com I ndeed, how we fashion the incision and, equally important, how we leave the incision at the end of surgery are pivotal factors in determining outcomes following cataract surgery. Not only are incisions crucial for the prevention of endophthalmitis, they are also responsible for surgically induced astigmatism and surface symptoms. Often, despite a perfectly done cataract surgery, patients keep nagging you for some “grittiness” or “foreign body sensation”...I am sure we have all encountered this, and therefore, paying attention to our incisions still remains key. When looking at how most people prefer to create their incisions, I agree with the majority on the use of disposable steel keratomes. They give a good feel and control during incision making, which I feel sometimes may be difficult with diamond keratomes, especially in the hands of beginner surgeons. Further, one big advantage is the disposable nature of the keratomes, a factor that is becoming more and more important with increasing emphasis on single-use disposables. However, as has been rightly pointed out, it is the length and self-sealing nature of the incision that are important in the end. I personally prefer a single-plane incision design and feel that if the internal entry length is adequate, it is as self-sealing as a 2- or a 3-plane incision. Further, I also find that in my hands single-plane incisions give less amounts of astigmatism as well as surface symptoms to the patient postoperatively. When we talk of incision sizes, I feel that compared to the initial size that you start with, what is more relevant is what you end up with. Often, tight incisions cause oar locking, thereby causing difficulty in intraoperative manipulations, as well as more stretching and distortion of the stromal collagen. Also, you need to make sure that your phaco tips, sleeves, IOL delivery systems are all compatible with the particular incision size. IOL implantation also causes enlargement of the incision. In the end, a small but distorted incision is often more prone to leakage and thereby increases the risk of endophthalmitis. Also, surgically induced astigmatism may in fact be more in such incisions. Although my preferred incision size is 2.2 mm, I think that should not become an ego issue with surgeons. Choose what works best in your hands with your instrumentation and machinery. As femtosecond lasers are catching on in cataract surgery, there is yet another option for creation of clear corneal incisions. I have been enjoying the femtosecond lasers for cataract surgery for 3 years plus now. Currently, most platforms are approved for creation of capsulorhexis, nucleus fragmentation, and clear corneal incisions. If I have to compare manual versus femtosecond incisions, the one big advantage with femtosecond lasers is the ability to customize. Not only can we select the incision width, but also, the surgeon can decide the exact depth of the incision, as well as the length. Once the laser is docked onto the patient’s eye, a realtime, intraoperative anterior segment OCT guides the surgeon to select the design, length, width, and location of his/her incision. This I think is a great advantage of lasers over manual incisions. The biggest advantage with femtosecond lasers I feel is the ability to create customized astigmatic keratotomies. Unlike manual LRIs, there is no subjective element here and well-titrated incisions can be created to simultaneously deal with preexisting corneal astigmatism. However, one limitation of current femtosecond laser technology, particularly for incision creation, is the fact that it can only make clear corneal incisions. In the presence of any opacity in the media, including peripheral vascularization or dense arcus senilis, the laser cannot penetrate. Therefore, in such cases, I prefer to perform manual incisions, since I usually like to perform incisions just in front of the limbus. However, as the femtosecond laser technology evolves, I am sure incision making will become even more easy and predictable. Editors’ note: Dr. Vasavada has financial interests with Alcon (Fort Worth, Texas). continued on page 47