|Year : 2001 | Volume
| Issue : 3 | Page : 199-202
Finding the retinal break in rhegmatogenous retinal detachment
Sandeep Saxena, Harvey Lincoff
Department of Ophthalmology, New York Presbyterian Hospital-Cornell University Medical Center, New York, U.S.A
New York Presbyterian Hospital, 525 East 68[th] Street, Suite F-832, New York 10021, USA
Source of Support: None, Conflict of Interest: None
The development of subretinal fluid is governed by a limited number of anatomical factors and gravity. As a result, rhegmatogenous retinal detachments form in a predictable manner around the retinal break of their origin. The shape of the detachments points to the position of the break. The purpose of this review is to describe the characterstic contours of subretinal fluid in rhegmatogenous retinal detachments, and to highlight some rules and methodology which can help in the detection of the retinal break in phakic, psuedophakic and recurrent retinal detachments.
Keywords: Retinal break, rhegmatogenous retinal detachment, subretinal fluid.
|How to cite this article:|
Saxena S, Lincoff H. Finding the retinal break in rhegmatogenous retinal detachment. Indian J Ophthalmol 2001;49:199-202
The success of retinal surgery for rhegmatogenous retinal detachment depends on findings the retinal break. A precise drawing of the fundus and the position of the break will guide the surgeon at the time of surgery. Attempts should be made to search for additional breaks that might be present in addition to the primary break. There is one break in about 50% of detachments but 2 breaks in 30% and 3 or more breaks in 20% of the cases.
The characteristics of rhegmatogenous detachments are: (1) they have convex surface and borders: (2) they develop dependent shapes in relation to the position of the most superior retinal break; (3) they extend from ora towards optic disc; and (4) they are progressive. Nonrhegmatogenous retinal detachments tend to be confined and do not extend from ora to optic disc. Exudative detachments are dependent and symmetrical around 6 o'clock. If the patient is examined lying flat, the fluid spreads posteriorly and if the patient is turned onto one or another side, the fluid runs up symmetrically on either side.
The position of the retinal break can be deducted from the shape of the detachment because subretinal fluid forms in a predictable manner from the break of origin. The growth and eventual shape of retinal detachment is governed by the position of the retinal break, the effect of gravity on subretinal fluid in relation to the erect posture and the anatomical limits such as the disc, the ora serrata and any chorioretinal adhesions that might be present. The most superior break in a detachment with multiple breaks is designated the primary break because it would produce the same contour if it were a single break.
[TAG:2]Finding the break in retinal detachment[/TAG:2]
(A) Superior temporal and nasal detachment
The detachment that arises from a superior break first forms around the break, then extends to the ora and then towards the optic disc. The detachment may initially be restricted to one quadrant. Once a bullous detachment has begun to form, the effects of gravity and ocular motion cause a dependent progression. The detachment descends as a front that revolves around the inferior pole of the disc and rises on the opposite side. Fluid may rise as high on the opposite side of the disc as the level of the primary retinal break, but never as high as the fluid level on the primary side. The primary break will be found within 1½ clock hours, of the highest border of the detachment, in 98% cases (Figure).
(B) Detachments that cross the 12 o'clock radian and total detachment
Detachments that cross the 12 o'clock radian originate from breaks at or near 12 o'clock. These detachments can become total. The more posterior the break, the more it can deviate from 12 o'clock position and still cause a detachment that will cross the vertical radian. In 93% of cases, the hole of origin lies with great frequency within a triangle whose apex is at 12 o'clock position at ora and whose sides intersect the equator one hour to at either side of 12 o'clock (Figure).
Attempts to reattach to total retinal detachment by repairing a break in an inferior quadrant, which must be a secondary break, are doomed to failure barring the presence of unusual traction. When studying a total detachment, it is important to look for a wedge of attached retina near 12 o'clock. The presence of a wedge of attached retina converts the problem of searching for the break in three clock hours (1½ clock hours to either side of 12 o'clock) of suspect retina in a total retinal detachment to one of searching 1½ clock hours in a superolateral or nasal detachment.
(C) Inferior detachment
The subretinal fluid that arises from breaks below the level of the optic disc develops first around the break and then descends to the ora serrata. It advances across the eye and towards the disc, rising higher on that side of the disc where the break lies. Thus, the higher side points to the position of the retinal break. The break need only be 1 or 2 mm from the 6 o'clock position for it to cause a difference in fluid levels. When the levels are equal, the hole is at the 6 o'clock radian. Detachments that arise from inferior breaks progress slowly and may be recognized late. The higher side of the detachment predicts the side of the break in 95% cases (Figure).
Occasionally, what appears to be an inferior detachment, equal in height on both sides of the disc, arises from a superior break which connects with the detachment by a shallow peripheral sinus. A history of rapid development and the absence of pigment demarcation lines suggests the presence of a superior break. When an inferior detachment is bullous, the primary break is above the horizontal radian. Inferior detachments that emanate from the inferior holes are relatively shallow.
All retinal breaks need to be closed at surgery. To avoid the pitfall of repairing a secondary break and omitting the treatment of the primary one, it is important to organize the examination. First, draw the limits of the detachment, then search the appropriate area for the primary break. Second, search for additional breaks. In more than 50% cases these will be in the same latitude as the primary break and close to it. Goldmann 3-mirror contact lens can be used to detect tiny breaks in phakic and aphakic retinal detachments. Slitlamp biomicroscope beam with maximum illumination is used. On rare occasions when no break can be found, or when the breaks that are found do not fit the criteria for the primary break, it is advisable to explore the appropriate area at the operating table with cryopexy to elicit the break.
Prospective segmental buckling can be used to localize the breaks. Carrying out this procedure implies that only the extent of the area of probability should be buckled, since the primary break is localized there 95% of the time. For a superior temporal or nasal detachment, buckle the upper 1½ clock hours. With superior detachment that crosses the 12 o'clock radian, buckle 1½ hours on either side of 12 o'clock, i.e., buckle 3 clock hours. With an inferior detachment, buckle up to 3 clock hours beneath the higher border of the detachment to 6 o'clock. If the retina reattaches the next day then the break was buckled. Interrupted laser must be applied over the entire length of the prospective segmental buckle. This is not to secure the tamponaded breaks but any undetected breaks on it. If the retinal fails to reattach after prospective segmental buckling the area buckled probably does not contain the break or all of the breaks. The retina should be again examined using the biomicroscope and the various contact lenses.
The advancing meniscus of an expanding gas bubble or the receding meniscus of an intraocular gas bubble, being absorbed, can be used to find the level of retinal break in cases in which the break is not identified by usual examined techniques. When an advancing meniscus of an expanding bubble is used, small amount of perfluorocarbon gas is injected, into the vitreous cavity, without drainage of subretinal fluid. As the gas bubble expands it reattaches the retina from above downward. When the bubble covers the retinal break, it tamponades it and the remaining fluid below absorbs within hours. The level of the meniscus when the retina becomes reattached marks the level of the retinal break. When a receding meniscus is used, the bubble closes the break and maintains reattachments. The level of the meniscus when the redetachment first occurs indicates the level of the break.
[TAG:2]Finding the break in the pseudophakic eye with retinal detachment[/TAG:2]
Retinal breaks in pseudophakic eyes are almost invariably anterior to the equator. The wide field indirect contact lens (Volk Equator Plus scanning fundus lens, Mentor, Ohio, USA) with some tilting, provides a clear image for biomicroscopy anterior to the equator. The indirect optics provides an image around moderate lens opacities and through thin capsular opacities, similar to the view obtained with the indirect ophthalmoscope. Through a 6-mm pupil, it is possible to bring the anterior retina and frequently the ora serrata into view in pseudophakic eyes. Their value for examining the retina anterior to the equator in the pseudophakic eye has so for been underappreciated.
With the wide-field indirect contact lens, a short slitlamp beam with maximum illumination, lined up at zero angle with the oculars, is used. To extend the view the patient is asked to look one-half inch towards the area to be studied. The axis of the lens is tilted towards this area, which is depressed through the eyelids with the round end of a curved stick depressor. When an area of suspicion is obstructed by a dense posterior capsular opacification, it can be notched with the YAG laser. The opening need not be wide if the radian of the cut is oriented towards the area to be studied.
In the pseudophakic eye, the wide-field indirect contact lens can produce an image anterior to the equator for the slitlamp almost to the extent as can be obtained by viewing with an indirect ophthalmoscope. The keys to bringing the anterior retina into view are rotating the eye, tilting the axis of the lens a few degrees towards the area to be examined and applying scleral depression.
The wide field indirect contact lens augments the retinal examination for the psuedophakic eye by detecting small breaks that can be overlooked with indirect ophthalmoscopy. The indirect contact lens has an advantage over the Goldmann lens because it eliminates the blur of marginal astigmatism induced by the intraocular lens and because the indirect image suffers less interference from lenticular and capsular opacities. The image through the indirect contact lens is inverted, as it is with the indirect ophthalmoscope, and can be transferred directly to an inverted retinal chart.
[TAG:2]Finding the break in the eye with redetachment[/TAG:2]
Three patterns of detachment can emerge after a failed buckle surgery in eyes that undergo surgery without drainage:
- (1) When the superior border of a temporal or nasal detachment falls below the buckle and the surface of the residual detachment is convex to the ora and persists, it implies the presence of another break below the new superior border.
- (2) When the pattern of the detachment (lateral, superior, or inferior) converts to another pattern, it indicates the presence of an undetected break consistent with the new pattern.
- (3) When the borders of the detachment remain unchanged after buckling surgery and the buckle appears to be in a good position, the most probable cause is an undetected break above the buckle.
At least 88% of rhegmatogenous retinal detachments are relatively uncomplicated when they first present, and will respond to one or more segmental buckle augmented occasionally by an encircling band, with or without drainage of fluid. Failure in the drained eye is manifested by partial or complete redetachment and in the undrained eye by incomplete or no attachment. The pattern of the detached retina will remain the same upon mobilization after either procedure,
A minimum of extraocular surgery for a rhegmatogenous retinal detachment can yield attachment only if it is preceded by a maximum search for the retinal breaks.
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