A New Lens for Closed Pars Plana Felipe
I.
Tolentino, MD, Hal M. Freeman, prismatic type of peripheral view of
lens enables the vitreous cavity. The surface in contact with the cornea is concave. The opposite surface is piano but inclined to produce a prismatic effect of 15\s=deg\or 25\s=deg\.A cannula attached to the lens provides corneal irrigation. Although this lens was originally designed for vitrectomy use, it is also useful for diagnostic biomicroscopy of the vitreous and fundus in the office. \s=b\ A new
a more
(Arch Ophthalmol 97:2197-2198, 1979)
MD
usually
cient room to maneuver a scierai indentor while the two instruments are inside the vitreous cavity. This article describes a new plano¬ concave lens with prismatic properties that allow the surgeon to view the peripheral fundus and vitreous with¬ out scierai indentation.
Accepted
for publication May 21, 1979. From the Microsurgery Laboratory, Department of Retina Research, Eye Research Institute of Retina Foundation, and Retina Associates, Boston. Reprint requests to Librarian, ERI of Retina Foundation, 20 Staniford St, Boston, MA 02114.
Fig on
attached to a handle with a gimbal device (Fig 2). The wire holder allows the lens to be rotated around 360° so that the thick portion of the lens, which is used to view the peripheral fundus and vitreous cavity, can be positioned toward any meridian of the globe. The gimbal device permits the assistant to position the lens evenly and gently on the cornea. The handle, made of aluminum to minimize weight, is held by an assistant. It is 130 mm long so that the assistant's hand is outside the microscopic field. er
DESCRIPTION OF LENS
USE OF LENS
The lens is made of high-quality plastic material. Its piano surface is inclined 15°, giving the lens the con¬ figuration of a prism (Fig 1). The lens has a diameter of 11 mm and a radius of curvature of 8.2 mm, which is flat¬ ter than the curvature of the cornea so that air bubbles are prevented from becoming trapped between the lens and the cornea. To allow corneal irri¬ gation during vitrectomy, a cannula is attached to the thin portion of the lens. The cannula is connected to a suspended bottle containing irriga¬ tion fluid. The lens is mounted on a wire hold-
When the lens is used for vitrecto¬ my, it is sterilized by ethylene oxide gas. The lens is connected by sterile intravenous tubing to a suspended saline bottle for continuous corneal irrigation during surgery. The lens is applied to the cornea so that its handle is positioned on the side opposite the sclerotomy to avoid interfering with the vitreous instruments. The handle is inclined 45° or less from the corneal plane. In this way, the handle and the assistant's hand do not obstruct the surgeon's view through the micro¬
^
visual axis. Scierai indentation is
of limited value in bimanual
(two-instrument) closed vitrectomy because both of the surgeon's hands are occupied with an instrument. In addition, indentation by an assistant is impractical because there is insuffi¬
/"Hosed vitrectomy through the pars
plana requires a planoconcave con¬ tact lens and operating microscope to visualize the surgical field in the deep vitreous. Currently available plano¬ concave lenses do not permit the surgeon to view the equatorial and peripheral vitreous unless the equator of the globe is indented toward the
Vitrectomy
1 —Closed vitrectomy lenses with prismatic left is inclined 25°; the lens on right, 15°.
properties.
Lens
Fig
scope. The thin
portion of the lens permits
2.—Lenses with handle and
Downloaded From: http://archopht.jamanetwork.com/ by a DALHOUSIE UNIVERSITY-DAL-11762 User on 03/13/2016
irrigation
device.
the cornea and prevent air bubbles from forming under the lens. cate
CLINICAL EVALUATION
Fig 3.—Diagram shows extent of peripheral 15° lens; right, 25° lens. the surgeon to visualize the posterior fundus and central vitreous. To view the periphery, the thick portion of the lens is directed toward the area to be visualized (Fig 3). A more peripheral view may be obtained by placing the lens off center so that the thick portion is closer to the center of the cornea, or by replacing the 15° lens with a 25° inclined lens with a strong¬ er prismatic effect. Excessive pres¬ sure on the lens should be avoided, because it may increase the intraocu-
view of vitreous
cavity with
use
of lens. Left,
lar pressure to dangerous levels. Visualization may be hampered when the piano surface of the lens becomes contaminated by the dried residue of saline solution. When saline is spilled on the lens surface, it should be rinsed with distilled water immediately. When the lens is used for office biomicroscopy of the vitreous and fundus, continuous irrigation of the cornea is unnecessary. A 2% methylcellulose solution is placed on the concave surface of the lens to lubri-
To determine the best inclination of the lens surface for optimum central and peripheral view of the vitreous cavity, 15°, 20°, 25°, 30°, and 45° lenses were evaluated clinically. The 30° and 45° inclined lenses offered a more peripheral view than the 15°, 20°, and 25° lenses. However, the 30° and 45° lenses were impractical because the steep inclination of the piano surface limited the field of view, and their extensive thickness dis¬ torted the view of the periphery. The peripheral view the 20° lens offered was only slightly greater than that of the 15° lens. The best combination of lenses was the 15° lens, which gave an excellent view of the posterior equato¬ rial vitreous and fundus, and the 25° lens, which produced minimal distor¬ tion and allowed peripheral viewing beyond the equator (Fig 3). These lenses facilitated the removal or cutting of membranes in the periph¬ ery. Because the reflected rays from the inclined piano surface are directed outside the surgeon's visual axis, glare from reflected light is minimized. The lens
was
provided by Ocular
Ine, Redmond, Wash.
Downloaded From: http://archopht.jamanetwork.com/ by a DALHOUSIE UNIVERSITY-DAL-11762 User on 03/13/2016
Instruments
I.
Tolentino, MD, Hal M. Freeman, prismatic type of peripheral view of
lens enables the vitreous cavity. The surface in contact with the cornea is concave. The opposite surface is piano but inclined to produce a prismatic effect of 15\s=deg\or 25\s=deg\.A cannula attached to the lens provides corneal irrigation. Although this lens was originally designed for vitrectomy use, it is also useful for diagnostic biomicroscopy of the vitreous and fundus in the office. \s=b\ A new
a more
(Arch Ophthalmol 97:2197-2198, 1979)
MD
usually
cient room to maneuver a scierai indentor while the two instruments are inside the vitreous cavity. This article describes a new plano¬ concave lens with prismatic properties that allow the surgeon to view the peripheral fundus and vitreous with¬ out scierai indentation.
Accepted
for publication May 21, 1979. From the Microsurgery Laboratory, Department of Retina Research, Eye Research Institute of Retina Foundation, and Retina Associates, Boston. Reprint requests to Librarian, ERI of Retina Foundation, 20 Staniford St, Boston, MA 02114.
Fig on
attached to a handle with a gimbal device (Fig 2). The wire holder allows the lens to be rotated around 360° so that the thick portion of the lens, which is used to view the peripheral fundus and vitreous cavity, can be positioned toward any meridian of the globe. The gimbal device permits the assistant to position the lens evenly and gently on the cornea. The handle, made of aluminum to minimize weight, is held by an assistant. It is 130 mm long so that the assistant's hand is outside the microscopic field. er
DESCRIPTION OF LENS
USE OF LENS
The lens is made of high-quality plastic material. Its piano surface is inclined 15°, giving the lens the con¬ figuration of a prism (Fig 1). The lens has a diameter of 11 mm and a radius of curvature of 8.2 mm, which is flat¬ ter than the curvature of the cornea so that air bubbles are prevented from becoming trapped between the lens and the cornea. To allow corneal irri¬ gation during vitrectomy, a cannula is attached to the thin portion of the lens. The cannula is connected to a suspended bottle containing irriga¬ tion fluid. The lens is mounted on a wire hold-
When the lens is used for vitrecto¬ my, it is sterilized by ethylene oxide gas. The lens is connected by sterile intravenous tubing to a suspended saline bottle for continuous corneal irrigation during surgery. The lens is applied to the cornea so that its handle is positioned on the side opposite the sclerotomy to avoid interfering with the vitreous instruments. The handle is inclined 45° or less from the corneal plane. In this way, the handle and the assistant's hand do not obstruct the surgeon's view through the micro¬
^
visual axis. Scierai indentation is
of limited value in bimanual
(two-instrument) closed vitrectomy because both of the surgeon's hands are occupied with an instrument. In addition, indentation by an assistant is impractical because there is insuffi¬
/"Hosed vitrectomy through the pars
plana requires a planoconcave con¬ tact lens and operating microscope to visualize the surgical field in the deep vitreous. Currently available plano¬ concave lenses do not permit the surgeon to view the equatorial and peripheral vitreous unless the equator of the globe is indented toward the
Vitrectomy
1 —Closed vitrectomy lenses with prismatic left is inclined 25°; the lens on right, 15°.
properties.
Lens
Fig
scope. The thin
portion of the lens permits
2.—Lenses with handle and
Downloaded From: http://archopht.jamanetwork.com/ by a DALHOUSIE UNIVERSITY-DAL-11762 User on 03/13/2016
irrigation
device.
the cornea and prevent air bubbles from forming under the lens. cate
CLINICAL EVALUATION
Fig 3.—Diagram shows extent of peripheral 15° lens; right, 25° lens. the surgeon to visualize the posterior fundus and central vitreous. To view the periphery, the thick portion of the lens is directed toward the area to be visualized (Fig 3). A more peripheral view may be obtained by placing the lens off center so that the thick portion is closer to the center of the cornea, or by replacing the 15° lens with a 25° inclined lens with a strong¬ er prismatic effect. Excessive pres¬ sure on the lens should be avoided, because it may increase the intraocu-
view of vitreous
cavity with
use
of lens. Left,
lar pressure to dangerous levels. Visualization may be hampered when the piano surface of the lens becomes contaminated by the dried residue of saline solution. When saline is spilled on the lens surface, it should be rinsed with distilled water immediately. When the lens is used for office biomicroscopy of the vitreous and fundus, continuous irrigation of the cornea is unnecessary. A 2% methylcellulose solution is placed on the concave surface of the lens to lubri-
To determine the best inclination of the lens surface for optimum central and peripheral view of the vitreous cavity, 15°, 20°, 25°, 30°, and 45° lenses were evaluated clinically. The 30° and 45° inclined lenses offered a more peripheral view than the 15°, 20°, and 25° lenses. However, the 30° and 45° lenses were impractical because the steep inclination of the piano surface limited the field of view, and their extensive thickness dis¬ torted the view of the periphery. The peripheral view the 20° lens offered was only slightly greater than that of the 15° lens. The best combination of lenses was the 15° lens, which gave an excellent view of the posterior equato¬ rial vitreous and fundus, and the 25° lens, which produced minimal distor¬ tion and allowed peripheral viewing beyond the equator (Fig 3). These lenses facilitated the removal or cutting of membranes in the periph¬ ery. Because the reflected rays from the inclined piano surface are directed outside the surgeon's visual axis, glare from reflected light is minimized. The lens
was
provided by Ocular
Ine, Redmond, Wash.
Downloaded From: http://archopht.jamanetwork.com/ by a DALHOUSIE UNIVERSITY-DAL-11762 User on 03/13/2016
Instruments
