Journal article Open Access

A 3D Video Overlay of Angularly and Linearly graduated scales for precisely indicating accurate measures on the Ocular surface in order to Guide Ophthalmic Surgeons during Toric IOL implantation and Squint Surgeries

Sivagnanam Subbiah


There are a number of systems in the market that are used for toricIOL (intraocular lens) implantation. Many of these require expensive paraphernalia. In this article a new system of axis marking, the Toric Max system (Appasamy Associates) along with a new methodology to identify the numerical value of the exact Cyclotorsion angle involved in the human eye is also considered while the Toric IOL is placed at its designated Placement axis by viewing the 3D monitor during the surgery by the Surgeon and also a 3D overlay Marking Scale for Squint Correction surgery is discussed. It is a cost effective, non- contact digital Toric marking video overlay system with a high level of accuracy. It minimizes too much automation and acquisition of additional equipment. It uses operating surgeon`s skill and facilitates the documentation of captured images of toric IOL placement in the designated axis in real time during the surgical procedure. A 3D overlay marking scale-This conceptualization depicts a 3D Overlay Reference indication on the Human Eye while performing a Squint Surgery – The Overlay design facilitates as an indicator for muscle insertion. These set of measuring scales from 1 to 8mm graduations in steps of 0.5mm and 1 to 10mm graduations in steps of 0.5mm is overlayed over the Human eye image obtained using the 3D camera module attached to an Ophthalmic Operating microscope. It minimizes time taken for each Eye surgery as most of the squint surgeries are done on Pediatric Patients under general anesthesia hence this 3D visual guidance enhances accuracy level of the Squint correction as well as minimizes overall Surgical time involved. No ink marking required, Pooling of blood during the Squint surgery will tend to erase the markings made with the inked instruments so repeated marking is made which might induce an error. The inputs for this software include the entire patient database entry along with the K1 and K2 values of the Patient along with IOL power measurements of the eye undergoing surgery from an A-Scan device, Calculator outputs of any IOL manufacturers’ toric calculator are collected and fed to the built-in offline toric calculator provided in the Toric MAX equipment which are compiled and calculated then later the exact Toric IOL placement details and Cyclotorsion Landmark angles are exported to the VTA software module by the click of a button. A prominent landmark feature is identified from the patient’s eye as a “Landmark Angle”, the location of which is noted from the scale of the slit-lamp by aligning the thin slit beam in-line with a prominent landmark like a mole or a blood vessel in Eye. (Figure 1) This is considered to be the reference to compensate for the cyclotorsion effect. A circular angle-scale as a video overlay appears on the display of this equipment which will guide the surgeon in real-time for indicating the Toric IOL placement axis.

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