Intraoperative Visualization of Peripheral Retina with Wide-Angle Viewing Systems

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1 Intraoperative Visualization of Peripheral Retina with Wide-Angle Viewing Systems Homayoun Tabandeh, M.D., MS, Francesco Boscia, M.D. 1. Retina -Vitreous Associates Medical Group, Los Angeles, California, USA. 2. Department of Ophthalmology, University of Bari, Bari, Italy ABSTRA DISCUSSION BACKGROUND: Wide-angle viewing systems have significantly improved intraoperative visualization of peripheral retina. The static field of view for most systems is in the range 120 to 140 degrees. Intraoperative manipulations such as ocular rotation, lens tilting, and lens decenteration can further enhance peripheral viewing. From a surgical perspective it is more relevant to know the distance of an area of interest from the Ora Serrata, than from the optic disc. The current study evaluated the distance of the retina area that corresponded to A) the internal tip of the sclerotomy cannula and B) edge of the viewing field from the ora serrata. METHODS: Non-comparative, clinical case series. Participants: patients undergoing pars plana vitrectomy (PPV) and endolaser photocoagulation. Exclusion criteria included patients with pupil diameter <5mm. During PPV, the retina areas corresponding to the internal tip of the sclerotomy cannula and the edge of the viewing field were marked with endolaser photocoagulation. The ora serrata was visualized with scleral depression and the distance between the ora serrata and the laser marks were measured in cannula diameter units. The measurements were subsequently converted to millimeter units. RESULTS: 35 eyes of 35 patients were included in the study. Contact lens viewing system (OVI 130) was used in 23 eyes (group1) and a non-contact viewing system (BIOM) was used in 12 eyes (group2). The cannula tip was visualized in 22 (95%) eyes in group1, and in 10 (83%) eyes in group 2. The mean distance from the edge of the viewing field to ora serrata was 1.1 mm (range mm) for group 1 and 1.2 mm (range mm) for group 2. The mean distance from the cannula tip to ora serrata was 1.4 mm (range 0.3 to 2.9 mm) for the 32 subjects in which the tip of cannula could be visualized. The 3 eyes in which the cannula tip could not be visualized also had a longer field edge-ora distance. CONCLUSION: Internal tip of a sclerotomy cannula can serve as a useful landmark indicating proximity to the ora serrata. With the current wide-angle systems it is possible to visualize the peripheral retina to the vicinity of the vitreous base without the need for scleral depression in most cases. METHODS Non-comparative, clinical case series Participants: patients undergoing PPV and endolaser photocoagulation Exclusion criteria : patients with pupil diameter <5mm During PPV, the retina areas corresponding to the internal tip of the sclerotomy cannula and the edge of the viewing field were marked with endolaser photocoagulation. The ora serrata was visualized with scleral depression and the distance between the ora serrata and the laser marks were measured in cannula diameter units. The measurements were subsequently converted to millimeter units. Outcome measures: - Distance of cannula tip from the ora serrata - Distance of edge of the viewing field from the ora serrata A B C A) The tip of the sclerotomy cannula is visualized internally B) The retina area corresponding to the cannula tip () is marked with endo-laser photocoagulation C) Scleral depression is performed visualizing the ora serrata (). The distance between the laser marks and the measured in cannula diameters and converted into mm units. In this case the to distance is 1.5 CD A A B A) Laser mark corresponding to cannula tip () and edge of viewing field () B) Scleral depression showing the to distance = 4 CD, to = 2 CD A) Scleral depression showing the distance between the ora serrata () and the laser mark corresponding to cannula tip (). to distance = 1.5 CD, to = 0.5 CD RESULTS 35 eyes of 35 patients. Contact lens viewing system (OVI 130) was used in 23 eyes (group1) and a non-contact viewing system (BIOM) was used in 12 eyes (group2). Pupil diameter: Mean 7.2 mm, Range 5 9 mm Lens status: Phakic 19, PCIOL 13, ACIOL 3 Cannula tip was visualized in 22 (95%) eyes in group1, and in 10 (83%) eyes in group 2. The mean distance from the edge of the viewing field to ora serrata was 1.1 mm (range mm) for group 1 and 1.2 mm (range mm) for group 2. The mean distance from the cannula tip to ora serrata was 1.4 mm (range 0.3 to 2.9 mm) for the 32 subjects in which the tip of cannula could be visualized. The 3 eyes in which the cannula tip could not be visualized also had a longer field edge-ora distance. Cannula Tip Visualized Cannula Tip OVI % 1.3 mm ( ) BIOM 83% 1.5 mm ( ) Edge of Field 1.1 mm (0 2.9) 1.2 mm ( ) Visualization of peripheral retina is an integral part of vitreoretinal surgery. Much important surgical pathology occurs in the retina area between the equator and the vitreous base Retinal tears occur most commonly between the equator and the posterior margin of the vitreous base Vitreous base A zone of 4-6 mm straddling the ora serrata Region of firmest attachment of vitreous to the retina Vitreo-retinal traction at the posterior margin of the vitreous base may cause retinal tear posterior to the VB Traditionally scleral depression is performed in order to visualize the vitreous base Wide-angle viewing systems have significantly improved intraoperative visualization of peripheral retina The static field of view for most systems is in the range 120 to 140 degrees Intraoperative manipulations such as ocular rotation, lens tilting, and lens decenteration further enhance peripheral viewing From a surgical perspective it is more relevant to know the distance of an area of interest from the Ora Serrata, than from the optic disc Findings of the current study indicate that it is possible to visualize the peripheral retina to within 1-2 mm of the ora serrata (within the vicinity of the vitreous base without the need for scleral depression There does not seem to be a major difference in the extent of visualization of the peripheral retina between the contact vs. noncontact viewing systems CONCLUSION Vitreous base 4-6 mm Dissection of vitreous base often advocated in surgical management of anterior PVR Contracted vitreous base / overlying PVR membrane may contribute to vitreo-retinal traction and persistent RD Shaving / trimming of vitreous base has also been advocated by many as part of PPV for routine RRD Wilkinson / Rice Retinal Detachment During pars plana vitrectomy the internal tip of a sclerotomy cannula can serve as a useful landmark indicating proximity to the ora serrata. With the current wide-angle systems it is possible to visualize the peripheral retina to the vicinity of the vitreous base without the need for scleral depression in most cases

2 BACKGROUND Wide-angle viewing systems have significantly improved intraoperative visualization of peripheral retina. The static field of view for most systems is in the range 120 to 140 degrees. Intraoperative manipulations such as ocular rotation, lens tilting, and lens decenteration can further enhance peripheral viewing. From a surgical perspective it is relevant to know the distance of an area of interest from the Ora Serrata. The current study evaluated the distance of the retina area that corresponded to A) the internal tip of the sclerotomy cannula and B) edge of the viewing field from the ora serrata.

3 METHODS Non-comparative, clinical case series. Participants: patients undergoing PPV / EL Exclusion: pupil diameter <5mm During PPV, the retina areas corresponding to the internal tip of the sclerotomy cannula and the edge of the viewing field were marked with endolaser photocoagulation. The ora serrata was visualized with scleral depression and the distance between the ora serrata and the laser marks were measured in cannula diameter units. The measurements were subsequently converted to millimeter units.

4 RESULTS Serrata Cannula Tip Edge of Field Cannula Tip Visualized Mean (mm) 1.4 mm 1.2 mm OVI 22 (95%) BIOM 10 (83%) Median (mm) Range (mm)

5 CONCLUSION Internal tip of a sclerotomy cannula can serve as a useful landmark indicating proximity to the ora serrata. With the current wide-angle systems it is possible to visualize the peripheral retina to the vicinity of the vitreous base without the need for scleral depression in most cases.