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Slit lamp use
EMERGENCY METHODS AND TECHNIQUES
Slit Lamp Use Alan M. Mindlin, MD* David W. Lamberts, MD* Stanley Grandon, MD* Detroit, Michigan
The adjustment of the slit lamp and m e t h o d of patient examination, including staining the e y e with fluorescein sodium, are outlined. The slit lamp can be u s e d b y e m e r g e n c y p h y s i c i a n s to d i a g n o s e c o m m o n e y e e m e r g e n c i e s such as foreign bodies, corneal ulcers, keratitis, corneal a b r a s i o n s a n d lacerations.
INTRODUCTION The slit l a m p m y s t i f i e s and terrifies p h y s i c i a n s u n f a m i l i a r w i t h its use. A t first glance, the c o m b i n a t i o n of lights, dials, and s w i n g i n g a r m s m a k e s this i n s t r u m e n t seem complex. In addition, the n u m b e r of o p p o r t u n i t i e s to use the slit l a m p v a r i e s from occasiona l l y to frequently, d e p e n d i n g upon the a m o u n t of ocular p r o b l e m s seen in the emergency department. For these reasons, m a n y e m e r g e n c y p h y s i c i a n s avoid u s i n g it, even w h e n available. The slit l a m p is a h i g h l y refined, lighted, magnification system that should be r e g a r d e d s i m p l y as a n o t h e r tool of the physician, to be used to ext e n d his diagnostic abilities (Figure 1). A l t h o u g h t h e slit l a m p is e x t r e m e l y v e r s a t i l e in t h e o p h t h a l m o l o g i s t ' s hands, e m e r g e n c y p h y s i c i a n s can ignore most of t h e fine points for t h e i r purposes.
*Kresge Eye Institute, Wayne State Umversity School of Medicine, Detroit, Michigan. Address for reprints: Alan M. Mindlin, MD, 1701 Baldwin, Suite 206, Pontiac, Michigan, 48055.
Page 336 Volume 4 Number 4
The slit l a m p is more p r o p e r l y called an illuminated biomicroscope. The n a m e slit l a m p is based on its a b i l i t y to focus l i g h t into a n a r r o w slit. The ins t r u m e n t allows the u s e r to view the a n t e r i o r s e g m e n t of t h e eye, u n d e r magnification, while i l l u m i n a t i n g t h e eye w i t h l i g h t from a n oblique angle. By v a r y i n g t h e light, its angle, a n d distance from the eye, the u s e r can o b t a i n much information.
the p a t i e n t fixes his gaze on a dista~ object (the fixation target), the lighh t u r n e d on a n d t h e i n s t r u m e n t p0sl tioned. The i n d e x finger of the physl cian's free h a n d is used to elevate t~ p a t i e n t s u p p e r lid, a n d if necessary the t h u m b is placed on the lower and both fingers g e n t l y spread. Thl, will expose t h e e n t i r e anterior se
Adjustment of the Slit Lamp To use the slit lamp, the p h y s i c i a n first adjusts the eye pieces (oculars) to the a p p r o p r i a t e w i d t h (Figure 2). If this isn't done, t h e u s e r m a y see double or see only t h r o u g h one ocular, thus losing depth perception. The n u m b e r s on t h e oculars r e p r e s e n t degrees of a d j u s t m e n t to s u b s t i t u t e for the eye glass prescription of viewers. If the p h y s i c i a n does not w e a r glasses, or prefers to view w i t h glasses, t h e r e a d i n g s on each ocular should be adj u s t e d to zero. F o l l o w i n g t h i s , t h e m a g n i f i c a t i o n selector is set on low power. To position the p a t i e n t for e x a m i n a tion, his chin is placed in the chin r e s t w i t h his forehead t i g h t l y a g a i n s t the bar. The b a r should cross his forehead j u s t above his brow ( F i g u r e 3). W h i l e
F i g . 1. Slit lamp.
July/August 1975
be moistened with either saline or an eye irrigating solution, such as an isotonic solution of boric acid, potassium chloride, and sodium carbonate (Dacriose), using one drop per strip. Water should not be used because it causes epithelial damage and can produce iatrogenic cornea1 staining. With the patient looking up, the lower lid is gently pulled down, and the strip placed in the lower conjunctival sac (Figure 61. The dye is distributed evenly over the cornea when the patient blinks. Topical anesthetic should not be instilled prior to the use of fluorescein, because this, too, will cause a stain pattern.
1‘g. 2. Oculars
of a slit lamp.
ent of the eye with a minimum of auma and discomfort to the patient i gure 41. are two movable arms on the . The larger arm contains the the biomicroscope, and the er arm contains the light source. ing arm is positioned to the cornea, where it The light source arm is tit is 45” away from the the physician is lookctly through the oculars, the lstrument can be moved forward or kkward, using the “joy stick” (FigFe51 In this manner the slit lamp 1hbe focused. The instrument should 1 adjusted so the light is focused
go4 Placement
QPJuly/August
of fingers I 975
for holdcng
Fig. lamp
3. Patient examination.
in position
for
slit
sharply on the cornea. The only other adjustment required is for the width of the slit. This control is always located on the illumination arm. The slit width should be set for 10 mm. Patient
Examination
One essential skill the physician should master before beginning the slit lamp examination is cornea1 staining with fluorescein. All “red eyes” must be stained. Fluorescein sodium, used for stammg, comes in strips of impregnated paper. Solutions should not be used, because of the incidence of fluorescein bottle contamination by Pseudomonas. The fluorescein (Fluor-l-strip) should
lid open.
Fig. 5. “Joy stick”
Under white light, the stain appears light green, but under cobalt blue light, it glows a bright, almost iridescent, yellow-green. Staining is due to breaks in the epithelial cell layer, so that the fluorescein pools in these areas and lights up brightly under cobalt blue light. All slit lamps have blue filters. Although it is not within the scope ofthis paper to discuss the differential diagnosis of the “red eye,” some common ocular disorders will be mentioned, especially in relation to their diagnosis with the slit lamp. Foreign bodies. The slit lamp is mvaluable to both find and remove foreign bodies, many of which are too small to be seen with the naked eye. Once found with the slit beam, the foreign body can be easily removed with a cotton tip applicator or a 21 gauge needle under direct vision. The eye should be patched, and the patient referred to an ophthalmologist for follow-up.
of a slLt lamp. Volume
4 Number
4 Page 337
NSM F i g . 6. Eye staining with moistened flourescein sodium impregnated paper strip placed in the lower conjunctival sac.
F i g . 7. "Dendrite" stain pattern.
s t a i n w i t h fluorescein. If the lesl0n~ in the c e n t r a l p a r t of t h e cornea, It 1~ b a c t e r i a l ulcer, not a n abrasion, unt[ p r o v e n otherwise. These are p0te~ t i a l l y e y e - t h r e a t e n i n g diseases a4 should be seen by an ophthalmol%4 i m m e d i a t e l y ( F i g u r e 8). K e r a t i t i s . W h e n the s t a i n pattern diffused over most of the corneal su~ face and a p p e a r s as several pinp0]r spots, a viral etiology should be cons dered. A n i d e n t i c a l picture, howevel ~can occur w i t h c h e m i c a l or ultra~01e damage. All can be t r e a t e d with a~ tibiotic drops a n d patching, and the the p a t i e n t referred. F i g . 8. "Punched our' corneal lesion statn pattern.
C o r n e a l u l c e r s . By f a r t h e m o s t c o m m o n c o r n e a l u l c e r s e e n in t h e e m e r g e n c y d e p a r t m e n t is the dendritic ulcer resulting from a herpes s i m p l e x v i r u s infection ( F i g u r e 7). These p a t i e n t s p r e s e n t w i t h decreased visual acuity, red, p a i n f u l eyes and show a classic s t a i n i n g p a t t e r n on slit l a m p e x a m i n a t i o n . T h e p a t t e r n is k n o w n as a ~ d e n d r i t e , " a n d is associated w i t h decreased corneal sensitivity. P a t i e n t s w i t h this condition s h o u l d be s e e n i m m e d i a t e l y " b y an ophthalmologist.
Corneal ulcers caused by other org a n i s m s u s u a l l y p r o d u c e necrotic, " p u n c h e d out" c o r n e a l lesions t h a t
Page 338 Volume 4 Number 4
N~t~l F i g . 9. Corneal abrasion stain pattern.
July/August 1975 J~
~ e a l a b r a s i o n s . These p a t i e n t s or .... ~th the chief c o m p l a i n t of a s¢~ 'bod~,, s e n s a t i o n in the eye. .e~g.n~amination m a y be w i t h i n ~llar ~ . . . ~ al hm~ts unless s h t l a m p exam1f~t~o~L~'r~,~~"erf°rmed' ~' If no stare" is" presthe symptoms m a y be due to a '~.eye syndrome" or a n i m p e n d i n g ~! infection, n e i t h e r of which is ~ent If a vertical line, or a series of itical hnes are p r e s e n t (Figure 9), a ign body is i m b e d d e d u n d e r the er lid. When the p h y s i c i a n everts lid and e x a m i n e s the mucosal surewlth the s h t lamp, its location will obvious. Other corneal abrasions Lll stain d e e p l y w i t h f l u o r e s c e i n . i
"
T h e i r size and location should be indicared on the p a t i e n t ' s chart. C o r n e a l l a c e r a t i o n s . Occasionally, the possibility of a through and t h r o u g h corneal l a c e r a t i o n will arise, w i t h t h e o b v i o u s s i g n s of a f i a t c h a m b e r a n d orbital contents extruding from the wound. This laceration m a y resemble a n abrasion, b u t if the eye is k e p t open and t h e s t a i n e d a r e a o b s e r v e d for 30 to 60 seconds, the f l u o r e s c e i n w i l l be r e p l a c e d . The aqueous h u m o r will a c t u a l l y p u m p out t h r o u g h the wound a n d replace the dye. This is k n o w n as a ~'positive Sidel test." This condition r e p r e s e n t s a true
i!rl~ta:"In the May/JuneJACEP Table of Contents, uree.We apologize for the premature award. - -
o p h t h a l m i c emergency. If the iris is seen to be l i t e r a l l y p l a s t e r e d a g a i n s t the cornea in this area, the dye will not be replaced since the iris acts as a seal. This s i t u a t i o n indicates a corneal lace r a t i o n u n t i l proven otherwise.
CONCLUSION
The slit l a m p is a v a l u a b l e instrum e n t in t h e e m e r g e n c y d e p a r t m e n t for the diagnosis of common eye emergencles. E m e r g e n c y p h y s i c i a n s should be f a m i l i a r w i t h its use a n d know its limitations and advantages.
Judith M. Jelenko, BS, BSN, was mistakenly assigned an MS de-
Managing Editor
?---_.___ ~PJuly/August 1975
Volume 4 Number 4 Page 339
Slit Lamp Use Alan M. Mindlin, MD* David W. Lamberts, MD* Stanley Grandon, MD* Detroit, Michigan
The adjustment of the slit lamp and m e t h o d of patient examination, including staining the e y e with fluorescein sodium, are outlined. The slit lamp can be u s e d b y e m e r g e n c y p h y s i c i a n s to d i a g n o s e c o m m o n e y e e m e r g e n c i e s such as foreign bodies, corneal ulcers, keratitis, corneal a b r a s i o n s a n d lacerations.
INTRODUCTION The slit l a m p m y s t i f i e s and terrifies p h y s i c i a n s u n f a m i l i a r w i t h its use. A t first glance, the c o m b i n a t i o n of lights, dials, and s w i n g i n g a r m s m a k e s this i n s t r u m e n t seem complex. In addition, the n u m b e r of o p p o r t u n i t i e s to use the slit l a m p v a r i e s from occasiona l l y to frequently, d e p e n d i n g upon the a m o u n t of ocular p r o b l e m s seen in the emergency department. For these reasons, m a n y e m e r g e n c y p h y s i c i a n s avoid u s i n g it, even w h e n available. The slit l a m p is a h i g h l y refined, lighted, magnification system that should be r e g a r d e d s i m p l y as a n o t h e r tool of the physician, to be used to ext e n d his diagnostic abilities (Figure 1). A l t h o u g h t h e slit l a m p is e x t r e m e l y v e r s a t i l e in t h e o p h t h a l m o l o g i s t ' s hands, e m e r g e n c y p h y s i c i a n s can ignore most of t h e fine points for t h e i r purposes.
*Kresge Eye Institute, Wayne State Umversity School of Medicine, Detroit, Michigan. Address for reprints: Alan M. Mindlin, MD, 1701 Baldwin, Suite 206, Pontiac, Michigan, 48055.
Page 336 Volume 4 Number 4
The slit l a m p is more p r o p e r l y called an illuminated biomicroscope. The n a m e slit l a m p is based on its a b i l i t y to focus l i g h t into a n a r r o w slit. The ins t r u m e n t allows the u s e r to view the a n t e r i o r s e g m e n t of t h e eye, u n d e r magnification, while i l l u m i n a t i n g t h e eye w i t h l i g h t from a n oblique angle. By v a r y i n g t h e light, its angle, a n d distance from the eye, the u s e r can o b t a i n much information.
the p a t i e n t fixes his gaze on a dista~ object (the fixation target), the lighh t u r n e d on a n d t h e i n s t r u m e n t p0sl tioned. The i n d e x finger of the physl cian's free h a n d is used to elevate t~ p a t i e n t s u p p e r lid, a n d if necessary the t h u m b is placed on the lower and both fingers g e n t l y spread. Thl, will expose t h e e n t i r e anterior se
Adjustment of the Slit Lamp To use the slit lamp, the p h y s i c i a n first adjusts the eye pieces (oculars) to the a p p r o p r i a t e w i d t h (Figure 2). If this isn't done, t h e u s e r m a y see double or see only t h r o u g h one ocular, thus losing depth perception. The n u m b e r s on t h e oculars r e p r e s e n t degrees of a d j u s t m e n t to s u b s t i t u t e for the eye glass prescription of viewers. If the p h y s i c i a n does not w e a r glasses, or prefers to view w i t h glasses, t h e r e a d i n g s on each ocular should be adj u s t e d to zero. F o l l o w i n g t h i s , t h e m a g n i f i c a t i o n selector is set on low power. To position the p a t i e n t for e x a m i n a tion, his chin is placed in the chin r e s t w i t h his forehead t i g h t l y a g a i n s t the bar. The b a r should cross his forehead j u s t above his brow ( F i g u r e 3). W h i l e
F i g . 1. Slit lamp.
July/August 1975
be moistened with either saline or an eye irrigating solution, such as an isotonic solution of boric acid, potassium chloride, and sodium carbonate (Dacriose), using one drop per strip. Water should not be used because it causes epithelial damage and can produce iatrogenic cornea1 staining. With the patient looking up, the lower lid is gently pulled down, and the strip placed in the lower conjunctival sac (Figure 61. The dye is distributed evenly over the cornea when the patient blinks. Topical anesthetic should not be instilled prior to the use of fluorescein, because this, too, will cause a stain pattern.
1‘g. 2. Oculars
of a slit lamp.
ent of the eye with a minimum of auma and discomfort to the patient i gure 41. are two movable arms on the . The larger arm contains the the biomicroscope, and the er arm contains the light source. ing arm is positioned to the cornea, where it The light source arm is tit is 45” away from the the physician is lookctly through the oculars, the lstrument can be moved forward or kkward, using the “joy stick” (FigFe51 In this manner the slit lamp 1hbe focused. The instrument should 1 adjusted so the light is focused
go4 Placement
QPJuly/August
of fingers I 975
for holdcng
Fig. lamp
3. Patient examination.
in position
for
slit
sharply on the cornea. The only other adjustment required is for the width of the slit. This control is always located on the illumination arm. The slit width should be set for 10 mm. Patient
Examination
One essential skill the physician should master before beginning the slit lamp examination is cornea1 staining with fluorescein. All “red eyes” must be stained. Fluorescein sodium, used for stammg, comes in strips of impregnated paper. Solutions should not be used, because of the incidence of fluorescein bottle contamination by Pseudomonas. The fluorescein (Fluor-l-strip) should
lid open.
Fig. 5. “Joy stick”
Under white light, the stain appears light green, but under cobalt blue light, it glows a bright, almost iridescent, yellow-green. Staining is due to breaks in the epithelial cell layer, so that the fluorescein pools in these areas and lights up brightly under cobalt blue light. All slit lamps have blue filters. Although it is not within the scope ofthis paper to discuss the differential diagnosis of the “red eye,” some common ocular disorders will be mentioned, especially in relation to their diagnosis with the slit lamp. Foreign bodies. The slit lamp is mvaluable to both find and remove foreign bodies, many of which are too small to be seen with the naked eye. Once found with the slit beam, the foreign body can be easily removed with a cotton tip applicator or a 21 gauge needle under direct vision. The eye should be patched, and the patient referred to an ophthalmologist for follow-up.
of a slLt lamp. Volume
4 Number
4 Page 337
NSM F i g . 6. Eye staining with moistened flourescein sodium impregnated paper strip placed in the lower conjunctival sac.
F i g . 7. "Dendrite" stain pattern.
s t a i n w i t h fluorescein. If the lesl0n~ in the c e n t r a l p a r t of t h e cornea, It 1~ b a c t e r i a l ulcer, not a n abrasion, unt[ p r o v e n otherwise. These are p0te~ t i a l l y e y e - t h r e a t e n i n g diseases a4 should be seen by an ophthalmol%4 i m m e d i a t e l y ( F i g u r e 8). K e r a t i t i s . W h e n the s t a i n pattern diffused over most of the corneal su~ face and a p p e a r s as several pinp0]r spots, a viral etiology should be cons dered. A n i d e n t i c a l picture, howevel ~can occur w i t h c h e m i c a l or ultra~01e damage. All can be t r e a t e d with a~ tibiotic drops a n d patching, and the the p a t i e n t referred. F i g . 8. "Punched our' corneal lesion statn pattern.
C o r n e a l u l c e r s . By f a r t h e m o s t c o m m o n c o r n e a l u l c e r s e e n in t h e e m e r g e n c y d e p a r t m e n t is the dendritic ulcer resulting from a herpes s i m p l e x v i r u s infection ( F i g u r e 7). These p a t i e n t s p r e s e n t w i t h decreased visual acuity, red, p a i n f u l eyes and show a classic s t a i n i n g p a t t e r n on slit l a m p e x a m i n a t i o n . T h e p a t t e r n is k n o w n as a ~ d e n d r i t e , " a n d is associated w i t h decreased corneal sensitivity. P a t i e n t s w i t h this condition s h o u l d be s e e n i m m e d i a t e l y " b y an ophthalmologist.
Corneal ulcers caused by other org a n i s m s u s u a l l y p r o d u c e necrotic, " p u n c h e d out" c o r n e a l lesions t h a t
Page 338 Volume 4 Number 4
N~t~l F i g . 9. Corneal abrasion stain pattern.
July/August 1975 J~
~ e a l a b r a s i o n s . These p a t i e n t s or .... ~th the chief c o m p l a i n t of a s¢~ 'bod~,, s e n s a t i o n in the eye. .e~g.n~amination m a y be w i t h i n ~llar ~ . . . ~ al hm~ts unless s h t l a m p exam1f~t~o~L~'r~,~~"erf°rmed' ~' If no stare" is" presthe symptoms m a y be due to a '~.eye syndrome" or a n i m p e n d i n g ~! infection, n e i t h e r of which is ~ent If a vertical line, or a series of itical hnes are p r e s e n t (Figure 9), a ign body is i m b e d d e d u n d e r the er lid. When the p h y s i c i a n everts lid and e x a m i n e s the mucosal surewlth the s h t lamp, its location will obvious. Other corneal abrasions Lll stain d e e p l y w i t h f l u o r e s c e i n . i
"
T h e i r size and location should be indicared on the p a t i e n t ' s chart. C o r n e a l l a c e r a t i o n s . Occasionally, the possibility of a through and t h r o u g h corneal l a c e r a t i o n will arise, w i t h t h e o b v i o u s s i g n s of a f i a t c h a m b e r a n d orbital contents extruding from the wound. This laceration m a y resemble a n abrasion, b u t if the eye is k e p t open and t h e s t a i n e d a r e a o b s e r v e d for 30 to 60 seconds, the f l u o r e s c e i n w i l l be r e p l a c e d . The aqueous h u m o r will a c t u a l l y p u m p out t h r o u g h the wound a n d replace the dye. This is k n o w n as a ~'positive Sidel test." This condition r e p r e s e n t s a true
i!rl~ta:"In the May/JuneJACEP Table of Contents, uree.We apologize for the premature award. - -
o p h t h a l m i c emergency. If the iris is seen to be l i t e r a l l y p l a s t e r e d a g a i n s t the cornea in this area, the dye will not be replaced since the iris acts as a seal. This s i t u a t i o n indicates a corneal lace r a t i o n u n t i l proven otherwise.
CONCLUSION
The slit l a m p is a v a l u a b l e instrum e n t in t h e e m e r g e n c y d e p a r t m e n t for the diagnosis of common eye emergencles. E m e r g e n c y p h y s i c i a n s should be f a m i l i a r w i t h its use a n d know its limitations and advantages.
Judith M. Jelenko, BS, BSN, was mistakenly assigned an MS de-
Managing Editor
?---_.___ ~PJuly/August 1975
Volume 4 Number 4 Page 339