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Effect of graded anterior transposition of the inferior oblique muscle on versions and vertical deviation in primary position
Effect of Graded Anterior Transposition of the Inferior Oblique Muscle on Versions and Vertical Deviation in Primary Position A d o l f o G u e m e s , M D , a n d K e n n e t h W. W r i g h t , M D
Introduction:There are various methods for weakening the inferior oblique muscle; here we describe the results of a graded anterior transposition. Methods: Charts of 21 children (37 eyes) who underwent graded anterior transposition of the inferior oblique muscle were reviewed. Graded anterior transposition consisted of reinsertion of the inferior oblique muscle at various points along the temporal aspect of the inferior rectus muscle; the more severe the overaction, the more anterior the placement of the new insertion. In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis. We analyzed the preoperative to postoperative change in inferior oblique overaction (versions) and vertical alignment in primary position. Results: Postoperatively, 18 of 21 patients had normal versions, 2 patients had -1 underaction of 1 eye, and 1 patient had +1 overaction of both eyes. Eleven patients (15 eyes) had a preoperative vertical deviation in primary position of 4 PD or more. Three of these patients had unilateral congenital superior oblique palsy and a preoperative hypertropia of 20 PD. They underwent unilateral graded anterior transposition with a mean postoperative vertical change of 18 PD. Three patients had asymmetric primary inferior oblique overaction with true hypertropia, 1 patient had amblyopia and primary inferior oblique overaction, and 4 patients had dissociated vertical deviation associated with inferior oblique overaction. All patients had improvement after surgery, with no significant vertical deviation in primary position. Conclusions: Graded anterior transposition of the inferior oblique muscle is effective in normalizing versions and correcting vertical deviations in primary position. (J AAPOS 1998;2:201-6)
here are a variety of procedures that are effective in reducing inferior oblique muscle overaction, including recessions, disinsertions, myectomies, denervation and extirpation, and anteriorization. 1 Parks 2 in a prospective controlled study compared inferior oblique muscle recessions, disinsertions, and myectomies. The 8 mm inferior oblique recession was found to be most effective with an undercorrection rate of 15%; however, this procedure had an unacceptably high undercorrection rate (75%) in patients with severe overaction of +4. 3 Denervation and extirpation have been suggested for severe inferior oblique overaction. This procedure, however, is irreversible, and it often results in limited elevation in the early postoperative period. 3 Anteriorization of the inferior oblique, as described by Elliot and Nankin 4 has been a popular alternative to correct moderate-to-severe inferior oblique overaction. This procedure has proved to
T
From the Cleveland Clinic"Foundation Eye Im-titute, Cleveland, Ohio. Presented at the annual meeting of the American Association for Pediatric Ophthalmology and Strabi~vnus, April 1997. Submitted April 6, 1997. Revision accepted February 16, 1998. Reprint requests: Kenneth W. Wright, MD, American Eye Institnte, 863Y W Third St, Suite 390 W,, Los Angeles, CA 90048. Copyright © I998 by the American Association for Pediatric Ophthalmology and Strabism~s. 1091-8Y31/98 SY.O0 + 0 75/1/92267
Journal of AAPOS
be a successful operation for reducing severe inferior oblique overaction and dissociated vertical deviation (DVD), but there has been an unacceptably high incidence of postoperative hypotropia and limited elevation if performed unilaterally. 5 Stager et al 6 demonstrated that the neurovascular bundle acts as an origin for the temporal portion of the inferior oblique muscle when its insertion is anteriorized. The stiffness of the inferior oblique neurovascular bundle acts as a functional tether, changing the function of the muscle from an elevator to a depressor. 7 Here we report results of a modified anterior transposition that we call the "graded anterior transposition" designed to reduce the complication of limited elevation. With this procedure, the new inferior oblique insertion line is oriented parallel to the inferior rectus muscle axis to avoid creating a "J" deformity (Figure 1). When the posterior fibers of the inferior oblique muscle are anteriorized, the anterior tip of the muscle creates the "J" deformity (Figure 2). In addition, the amount of anterior transposition is titrated to the amount of inferior oblique overaction or vertical deviation, never placing the new insertion anteriot to the inferior rectus insertion line. SUBJECTS AND METHODS We reviewed the charts of 50 patients who underwent graded anterior transposition of the inferior oblique mus-
August 1998 201
Journal ofAAPOS Volume 2 Number 4 August 1998
202 Guemesand Wright
m.
Vortex v.
n.
FIG 1. New inferior oblique insertion line is parallel to inferior rectus muscle axis. FI6 3. Inferior oblique and inferior rectus muscle seen from below. Different locations for inferior oblique reinsertion. Inferior obliqt
Neurofibrov bundl
FIG 2. Posterior fibers of inferior oblique muscle are anteriorized, creating "J" deformity.
cle for primary inferior oblique overaction, inferior oblique overaction associated with DVD, and unilateral congenital superior oblique palsy. All patients were operated by a single surgeon (K.W.) between August 1994 and June 1996. Exclusion criteria included previous inferior oblique surgery, infraplacement or supraplacement of the horizontal rectus muscles, or previous vertical muscle operation. Twenty-one patients (37 eyes) were included in the study. There were 13 boys and 8 girls, with ages ranging from 18 months to 9.5 years (mean 4.76 years).
Follow-up ranged from 3 to 12 months (mean 5.3 months). Fourteen patients had primary inferior oblique overaction, 10 patients with esotropia and 4 patients with exotropia. Four patients had DVD associated with inferior oblique overaction. Three patients had unilateral congenital superior oblique palsy with secondary inferior oblique overaction (Table 1). Three patients had symmetric, 14 patients had asymmetric, and 4 patients had unilateral graded anterior transposition. Fifteen patients also had simultaneous horizontal muscle surgery. Ocular motility examination included visual acuity, ductions, versions, and ocular deviation in primary position measured by alternate prism cover test. The presence of a significant V pattern (> 15 PD) was clinically observed and noted; however, it was not quantitated by prism cover testing in all children. Versions were graded preoperatively and postoperatively on a scale o f - 4 underaction to +4 overaction, with 0 being normal. When versions were checked, the adducting eye was partially covered to ensure fixation with the abducting eye. Vertical deviation in primary position was measured with alternate cover testing to disclose the full phoria. When a DVD was present, a base down prism and cover was placed over the eye to be measured. The cover was switched to the fixing eye, and the amount of base down prism was increased until no downward movement was seen under the eye behind the prism. Care was taken to distinguish DVD from a true hypertropia. The results of last examination were recorded for the study. The surgical technique has been previously described; it
Journal of AAPOS Volume 2 Number 4 August 1998
Guemes and Wright 203
TABLE 1. Diagnosis in 21 patients with graded anteriorizationof inferior oblique muscle
Primary inferior oblique overaction
No. of patients
Esotropia
Exotropia
11
3
Inferior Superior oblique oblique overaction palsy +DVD 3
4
consisted of moving the inferior oblique insertion to a location along the temporal border of the inferior rectus muscle. 8 T h e anterior transposition was classified by its relationship to the inferior rectus insertion (ie, at the inferior rectus insertion), 1 mm posterior, 2 mm posterior, 3 mm posterior, 4 mm posterior, or 4 mm posterior and 2 mm temporal (Figure 3). In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis so there was no "J" deformity. Placement of the inferior oblique was based on the severity of the overaction. The more the inferior oblique overacted, the more anterior the placement of the new insertion. V patterns and vertical deviations in primary position also influenced the amount of anterior transposition. For mild inferior oblique overaction, if it were associated with a significant V pattern, the new insertion was placed 4 mm posterior and 2 mm temporal or 4 mm posterior to the inferior rectus insertion. For moderate inferior oblique overaction, the new insertion was placed 3 mm posterior to the inferior rectus insertion. For severe inferior oblique overaction or inferior oblique overaction associated with DVD, the new insertion was placed 2 to 1 mm posterior to the inferior rectus insertion or at the temporal border of the inferior rectus insertion (except 1 eye with mild DVD).
RESULTS Versions
Thirty-seven eyes underwent graded anterior transposition, of which 11 (33%) had +3 or more overaction (Table 2). Postoperatively all eyes had no more than plus or minus 1 oblique dysfunction, and 33 of 37 eyes (89%) showed normal versions. The 11 eyes with +3 or more overaction received graded anterior transposition 2 mm posterior to the inferior rectus insertion to full anterior transposition. N o n e of these patients showed more than _+1 inferior oblique dysfunction after surgery, with 9 of 11 patients showing normal versions. N o patient had clinically significant limited elevation after surgery. This included 5 patients who underwent unilateral surgery, 2 patients at 1 mm posterior, 2 patients at 2 mm, and 1 patient at 4 mm posterior to the inferior rectus insertion. The amount of graded anterior transposition positively correlated with the degree of change in version, with the larger the anterior transposition the greater the change in versions. The correlation coefficient for anterior transposition and version was -0.60, P < .001 (Spearman's rank).
TABLE 2. Version changes in 37 eyes of 21 patients undergoing graded anteriorizationof inferior oblique muscle, by degree of anteriorization.
Version Patient Preoperative post- Version Anteriorization No Eye versions operative change Full
1 2 1 mm posterior 3 4 5 6 6 7 1 2 mm posterior 8 8 9 7 10 11 12 13 13 3 mm posterior 14 15 4 2 4 mm posterior 14 15 16 16 17 17 18 10 19 20 20 21 21 4 mm posterior, 9 2 mm temporal 18 OD, Righteye;OS, left eye.
OD OS OS OS OD OD OS OD OS OD OS OS OS OD OD 0D OD OS OS 0S OD OD OD OD OD OS OD OS 0S OS OD OD OS OS OD OD OD
+3 +2.5 +2.5 +3 +3 +3 +3 +3 +3 +3 +3 +2 +2.5 +2.5 +2 +2.5 +4 +3 +2.5 +1,5 +2 +1.5 +2 +1 +2 +2 +2 +2 +0.5 +1 +1 +1 +0.5 +2 +2 +1 +1.5
Normal Normal Normal Normal Normal +1 +1 Normal Normal Normal Normal Normal Normal Normal -1 Normal Normal Normal Normal Normal Normal -1 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal
3 2.5 2.5 3 3 2 2 3 3 3 3 2 2.5 2.5 3 2.5 4 3 2.5 1.5 2 2.5 2 1 2 2 2 2 0.5 1 1 1 0.5 2 2 1 1.5
A clinically evident "V" pattern was present preoperatively in patients with bilateral primary inferior oblique overaction. Postoperatively the pattern resolved, noted by clinical observation. None of the 3 patients with unilateral superior oblique palsy had a significant V pattern. Vertical Alignment Eleven patients (15 eyes) had a vertical deviation in primary position 4 PD or more (Table 3). Three patients with unilateral congenital superior oblique palsy had unilateral graded anterior transposition of 1 ram, 2 mm, and 3 mm posterior to the inferior rectus insertion for preoperative hypertropias of 20 PD. For more than +2 inferior oblique overaction, the new insertion was placed 2 to 1 mm posterior to the inferior rectus insertion; for milder overaction,
Journal ofAAPOS Volume 2 Number 4 August 1998
204 Guemesand Wright ]'ABLE3. Patientswith true hypertropia_>4PD associatedwith asymmetricor unilateral inferior oblique overaction
Primary position Patient No.
Diagnosis
Anteriorization posterior to inferior rectus insertion (mm)
Pre (PD)
Post(PD)
Change (PD)
Unilateral surgery
3 SOP OD 1 posterior RHT 20 Ortho 20 5 XT + V + amblyopia OD 1 posterior RHT 6 Ortho 6 11 SOP OD 3 posterior RHT 20 RHT 5 15 12 SOP OD 0.2 posterior RHT 20 RHT 2 18 Asymmetric surgery 7 ET + IOOA OD 1.0 posterior, OS 2.0 posterior RHT 4 Ortho 4 9 ET + IOOA OD 4 posterior 2 temporal, OS 2.0 posterior RHT 6 Ortho 6 10 ET + IOOA OD 2.0 posterior, OS 4.0 posterior RHT 6 Ortho 6 Pre, Preoperative;Post, postoperative;SOP,superiorobliquepalsy;OD, right eye;RHT,right hypertropia;Ortho, orthotropia;XT,exotropia, V,,"V" pattern;ET,esotropia.
TABLE 4. Gradedanteriorizationfor patients with DVD and associated inferior oblique overaction
Primary position Patient No.
Diagnosis
1
ET + DVD + IOOA
2
ET + DVD + IOOA
6
ET+ DVD + IOOA
13
ET + DVD + IOOA
Anteriorization posterior to inferior rectus insertion (mm) OD full OS 1.0 posterior OD 3 posterior OS full OS 1.0 posterior OS 1.0 posterior OD 2.0 posterior
OS 2.0 posterior Pre, Preoperative;Post, postoperative;ET,esotropia,OD, righteye;Ortho, orthotropia;OS, left eye.
the new insertion was placed 3 mm posterior to the inferior rectus insertion. Postoperatively, the anterior transposition changed the vertical deviation by 20 PD for 1 ram, 18 PD for 2 ram, and 15 PD for 3 mm anterior transposition (mean 18 PD). This resulted in good postoperative alignment in primary position, with 1 patient orthophoric, 1 patient with a right hypertropia of 4 PD, and 1 patient with a right hypertropia of 5 PD. One patient with exotropia, +3 primary inferior oblique overaction, and dense amblyopia had a unilateral anterior transposition of 1 mm posterior to the inferior rectus insertion. The vertical deviation in this patient was variable and measured approximately 6 PD preoperatively, and postoperatively there was no significant vertical deviation. Three patients with asymmetric primary inferior oblique overaction and a true hypertropia of 4 PD to 6 PD in primary position had asymmetric graded anterior transposition. Postoperatively the vertical deviation was eliminated in all patients, with a mean change of 5 PD. Four patients had bilateral surgery for primary inferior oblique overaction associated with DVD (range per patient 6 to t5 PD). All patients had a significant improvement after surgery (Table 4). Two patients showed no appreciable DVD with 6 to 10 PD improvement, and 2 patients had a small residual DVD (4 and 5 PD) with 7 and 10 PD improvement.
Pre (PD)
Post (PD)
Change (PD)
OD DVD 10 OS DVD 8 OD DVD 5 OS DVD 15 OS DVD 10 OS DVD 12 OD DVD 6
Ortho Ortho DVD 4 DVD 5 DVD 5 DVD 5 Ortho
10 8 1 10 5 7 6
OS DVD 3
Ortho
3
DISCUSSION Historically, severe inferior oblique overaction has been difficult to manage with procedures such as inferior oblique recession and myectomy.2, 3 More "powerful" procedures such as extirpation, denervation, and anterior transposition are effective in reducing overaction, but these procedures can result in inferior oblique underaction. 3-5 This is especially problematic for unilateral anterior transposition procedures, where the complication of postoperative limitation of elevation with a hypotropia in primary position is common. 5 In the current study we found the graded anterior transposition avoided the complication of postoperative limited elevation yet was effective in correcting both mild and severe inferior oblique overaction. Eleven eyes with +3 or more overaction had full anterior transposition to 2 mm posterior to the inferior rectus insertion. Postoperatively, all these severe cases showed no more than +1 oblique dysfunction, and 9 of the 11 eyes (82%) showed normal versions. It was reassuring to find that none of our patients had significant limitation of elevation or a hypotropia in primary position postoperatively. This included 3 patients who underwent large unilateral anterior transpositions of 1 mm, 2 mm, and 3 mm posterior to the inferior rectus insertion. We attribute the success of our graded anterior trans-
Journal of AAPOS Volume 2 Number 4 August 1998
positions to 4 factors. First, the amount of anterior transposition is tailored to the amount of inferior oblique overaction. Moving the inferior oblique insertion anterior to the equator, toward the inferior rectus insertion, progressively reduces the elevator function of the inferior oblique muscle. 4 Eyes with larger amounts of inferior oblique overaction receive larger anterior transpositions. In patients with minimal inferior oblique overaction it is not necessary to perform a full anterior transposition because this may result in limited elevation postoperatively. In these patients the inferior oblique muscle is only minimally anteriorized to 4 mm posterior to the inferior rectus insertion. The second factor is to place the new inferior oblique insertion perpendicular to the inferior rectus muscle to avoid anteriorizing the posterior muscle fibers (Figure 2). In contrast, if the new insertion is oriented parallel to the inferior rectus insertion, this tightens the posterior muscle fibers, creating a "J" deformity of the inferior oblique muscle (Figure 1). Stager et al 6 and Stidham et al 7 have shown the importance of the posterior muscle fibers and the neurovascular bundle in producing limited elevation after inferior oblique anterior transposition. The exact mechanism remains unknown, but anteriorizing the posterior fibers of the inferior oblique muscle probably tightens the neurovascular bundle and creates an active leash that pulls the eye downward on attempted elevation. 7 Our anterior transposition procedure avoids the "J" deformity by always keeping the posterior muscle fibers at least 3 mm posterior to the inferior rectus insertion (Figure 3). Third, it is important to avoid inadvertent resection of the inferior oblique muscle when securing the muscle with suture. If sutures are placed more than 3 mm proximal to the inferior oblique tendon, this will significantly shorten the inferior oblique muscle, creating restriction in elevation. Clear exposure of the inferior oblique insertion is essential to safely remove the inferior oblique muscle close to the sclera without a significant resection. The other important factor was that we do not replace the inferior oblique muscle anterior to the inferior rectus insertion. In patients with DVD and inferior oblique overaction the most we would anteriorize the inferior oblique muscle was to the inferior rectus insertion, not anterior to the insertion. Others have advocated anteriorizing the inferior oblique anterior to the inferior rectus insertion 9, 10; however, our experience is that this leads to limited elevation and is not necessary for most cases of DVD associated with inferior oblique overaction. We also found the graded inferior oblique anterior transposition procedure to be useful in patients with unilateral congenital superior oblique palsy and large vertical deviations in primary position. 11, 12 Three of our patients with unilateral congenital superior oblique palsy underwent an anterior transposition procedure of 1 to 3 mm posterior to the inferior rectus insertion for vertical deviation in primary position between 15 and 20 PD. This uni-
Guemes and Wright 205 lateral anterior transposition procedure resulted in a mean reduction in the vertical deviation of 18 PD, and in all 3 patients the postoperative residual deviation was less than 5 PD. Despite this large change in vertical deviation, only 1 of the 3 patients showed a -1 limitation to elevation in adduction (trace inferior oblique underaction). In contrast to the unilateral anterior transposition procedure, the asymmetric bilateral anterior transposition procedure did not result in large changes in the vertical deviation. Of 3 patients with bilateral asymmetric surgery for asymmetric inferior oblique overaction and a true hypertropia, the eye with the hypertropia would receive the stronger procedure (inferior oblique placed more anterior) than the fellow eye. Asymmetric anterior transposition of no more than 2 mm did reduce the vertical deviation but no more than 6 PD. Our results show that we should not expect asymmetric graded anteriorization of less than 2 mm to eliminate true vertical deviations of more than 6 PD. If the deviation in primary position is greater than 6 PD, consider adding a vertical rectus muscle to the surgical plan. Fortunately, it is unusual that patients with bilateral asymmetric inferior oblique overaction have large vertical deviations; therefore the asymmetric procedure usually is sufficient. For the treatment of DVD, previous reports have suggested a full anterior transposition procedure, even placing the new inferior oblique insertion anterior to the inferior rectus insertion. 9, 10 We used our graded anterior transposition procedure, limiting the anterior transposition to the inferior rectus insertion and keeping the new insertion parallel with the inferior rectus muscle axis. Despite this potentially less potent procedure, our results with DVD were good. Of 4 patients with bilateral DVD ranging between 10 PD and 15 PD in the worse eye, postoperatively 2 patients had no appreciable DVD and the other 2 patients had less than 5 PD of residual DVD. The mean improvement in DVD in these patients was 10 PD. We found that relatively large anterior transpositions were needed to correct DVD, but it was not necessary to move the inferior oblique anterior to the inferior rectus insertion. In patients with asymmetric DVD we performed an asymmetric anterior transposition procedure. Others have recommended graded inferior oblique recessions and anterior transpositions. 2, 13-15 The graded inferior oblique muscle recession is actually an anteriorization procedure because the new insertion site is significantly anterior to the original insertion, which is at the macula a few millimeters from the optic nerve. Parks' 10 mm inferior oblique recession, which is marked 3 mm posterior and 2 mm temporal to the temporal pole of the inferior rectus insertion, is, in fact, an anterior transposition procedure, is Apt and Call 14 recommended many different insertion sites, and these were a form of anterior transposition. Kratz et al9 graded the amount of anterior transposition of the posterior fibers of the inferior oblique muscle for DVD associated with inferior oblique overaction. Posterior fibers in the inferior oblique were inserted at 3
Journal of AAPOS Volume 2 Number 4 August 1998
206 Guemesand Wright different stations depending on the severity of the D V D . W e realize and respect that there are m a n y valid approaches to correcting inferior oblique overaction. O n the basis of data f r o m this study and our clinical experience, we suggest the following system o f graded anterior transposition of the inferior oblique. Primary inferior oblique overaction (IOOA) • I O O A versions +4 = full anterior transposition* (no "S" deformity) +3 = 1 m m posterior inferior rectus insertion +2 = 3 or 4 m m posterior inferior rectus insertion + 1 = 4 m m posterior inferior rectus insertion and 2 m m temporal to inferior rectus • Bilateral asymmetric p r i m a r y I O O A with hypertropia 5 to 6 P D = asymmetric anterior transposition at least 2 m m difference between fellow eyes DVD with IOOA • D V D : 10 to 15 P D = full anterior transposition (no "J" deformity) 4 to 10 P D = 1 to 2 m m posterior inferior rectus insertion Unilateral Congenital Superior Oblique Palsy • H y p e r t r o p i a in p r i m a r y position 15 to 20 P D with +3 I O O A = ipsilateral anterior transposition 1 to 2 m m posterior inferior rectus insertion
*Avoid unilateral full anterior transposition to avoid postoperative limitations of elevation.
@
References
1. Wright KW. Current approaches to inferior oblique muscle surgery. In: Hoyt CS, editor. Focal points 1986: clinical modules for ophthalmologists. San Francisco: American Academy of Ophthalmology; 1986. Vol 4, module 6. 2. Parks MM. The weakening surgical procedures for eliminating overaction of the inferior oblique muscle. Am J Ophthatmol 1972;73:107-22. 3. Del Monte MA, Parks MM. Denervation and extirpation of the inferior oblique: an improved weakening procedure for marked overaction. Ophthalmology 1983,90;1178-83. 4. Elliot RL, Nankin SJ. Anterior transposition of the inferior oblique. J Pediatr Ophthalmol Strabismus 1981;18:35-8. 5. Bremer DL, Rogers GL, Quick LD. Primary-position hypotropia after anterior transposition of the inferior oblique. Arch Ophthalmol
1986;t04:229-32. 6. Stager DR, Wealdey DR, Stager D. Anterior transposition of the inferior oblique: anatomic assessment of the neurovascular bundle. Arch Ophthalmol 1992;110:360-2. 7. Stidham DB, Stager DR, Kamm KE, Grange RW. Stiffness of the inferior oblique neurofibrovascular bundle. Invest Ophthalmol Vis Sci 1997;38:1314-20. 8. Wright KW. Inferior oblique surgery. In: Wright KW, editor. Color atlas of ophthalmic surgery, strabismus. Philadelphia: JB Lippincott; 1991. p. 173-99. 9. Kratz RE, Rogers GL, Bremer DL, Leguire LE. Anterior tendon displacement of the inferior oblique for DVD. J Pediatr Ophthalmol Strabismus 1989;26:212-7. 10. Mims JL, Wood RC. Bilateral anterior transposition of the inferior obliques. Arch Ophthalmol 1989:107:41-4. 11. Gonzalez C, Cinciprini C. Anterior transposition of the inferior oblique in the treatment of unilateral superior oblique palsy. J Pediatr Ophthalmol Strabismus 1995;32:107-13. 12. May MM, Beauchamp GR, Price RL. Recession and anterior transposition of the inferior oblique for treatment of superior oblique palsy. Graefes Arch Clin Exp Ophthalmol 1988;226:407-9. 13. Fink WH. Surgery of the vertical muscles of the eye. Springfield (IL): Charles C Thomas; 1962. 14. Apt L, Call NB. Inferior oblique muscle recession. AmJ Ophthalmol 1978;85:95-100. 15. Parks MM. Atlas of strabismus surgery. New York: Harper & Row; 1983.
An Eye on the Arts T h e Arts on the Eye
"You have given up [the town of] Bradfield altogether then?" "Too provincial m y boy! What's the good of a village practice with a miserable three thousand or so a year for a m a n that wants r o o m to s p r e a d ? . . . I've taken to the eye, m y boy. T h e r e ' s a fortune in the eye. A m a n grudges a halfcrown to cure his chest or his throat, but h e ' d spend his last dollar over his eye. T h e r e ' s m o n e y in ears, but the eye is a gold mine!" - - S i r Arthur C o n a n D o y l e (from The Stark Muno Letters)
Introduction:There are various methods for weakening the inferior oblique muscle; here we describe the results of a graded anterior transposition. Methods: Charts of 21 children (37 eyes) who underwent graded anterior transposition of the inferior oblique muscle were reviewed. Graded anterior transposition consisted of reinsertion of the inferior oblique muscle at various points along the temporal aspect of the inferior rectus muscle; the more severe the overaction, the more anterior the placement of the new insertion. In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis. We analyzed the preoperative to postoperative change in inferior oblique overaction (versions) and vertical alignment in primary position. Results: Postoperatively, 18 of 21 patients had normal versions, 2 patients had -1 underaction of 1 eye, and 1 patient had +1 overaction of both eyes. Eleven patients (15 eyes) had a preoperative vertical deviation in primary position of 4 PD or more. Three of these patients had unilateral congenital superior oblique palsy and a preoperative hypertropia of 20 PD. They underwent unilateral graded anterior transposition with a mean postoperative vertical change of 18 PD. Three patients had asymmetric primary inferior oblique overaction with true hypertropia, 1 patient had amblyopia and primary inferior oblique overaction, and 4 patients had dissociated vertical deviation associated with inferior oblique overaction. All patients had improvement after surgery, with no significant vertical deviation in primary position. Conclusions: Graded anterior transposition of the inferior oblique muscle is effective in normalizing versions and correcting vertical deviations in primary position. (J AAPOS 1998;2:201-6)
here are a variety of procedures that are effective in reducing inferior oblique muscle overaction, including recessions, disinsertions, myectomies, denervation and extirpation, and anteriorization. 1 Parks 2 in a prospective controlled study compared inferior oblique muscle recessions, disinsertions, and myectomies. The 8 mm inferior oblique recession was found to be most effective with an undercorrection rate of 15%; however, this procedure had an unacceptably high undercorrection rate (75%) in patients with severe overaction of +4. 3 Denervation and extirpation have been suggested for severe inferior oblique overaction. This procedure, however, is irreversible, and it often results in limited elevation in the early postoperative period. 3 Anteriorization of the inferior oblique, as described by Elliot and Nankin 4 has been a popular alternative to correct moderate-to-severe inferior oblique overaction. This procedure has proved to
T
From the Cleveland Clinic"Foundation Eye Im-titute, Cleveland, Ohio. Presented at the annual meeting of the American Association for Pediatric Ophthalmology and Strabi~vnus, April 1997. Submitted April 6, 1997. Revision accepted February 16, 1998. Reprint requests: Kenneth W. Wright, MD, American Eye Institnte, 863Y W Third St, Suite 390 W,, Los Angeles, CA 90048. Copyright © I998 by the American Association for Pediatric Ophthalmology and Strabism~s. 1091-8Y31/98 SY.O0 + 0 75/1/92267
Journal of AAPOS
be a successful operation for reducing severe inferior oblique overaction and dissociated vertical deviation (DVD), but there has been an unacceptably high incidence of postoperative hypotropia and limited elevation if performed unilaterally. 5 Stager et al 6 demonstrated that the neurovascular bundle acts as an origin for the temporal portion of the inferior oblique muscle when its insertion is anteriorized. The stiffness of the inferior oblique neurovascular bundle acts as a functional tether, changing the function of the muscle from an elevator to a depressor. 7 Here we report results of a modified anterior transposition that we call the "graded anterior transposition" designed to reduce the complication of limited elevation. With this procedure, the new inferior oblique insertion line is oriented parallel to the inferior rectus muscle axis to avoid creating a "J" deformity (Figure 1). When the posterior fibers of the inferior oblique muscle are anteriorized, the anterior tip of the muscle creates the "J" deformity (Figure 2). In addition, the amount of anterior transposition is titrated to the amount of inferior oblique overaction or vertical deviation, never placing the new insertion anteriot to the inferior rectus insertion line. SUBJECTS AND METHODS We reviewed the charts of 50 patients who underwent graded anterior transposition of the inferior oblique mus-
August 1998 201
Journal ofAAPOS Volume 2 Number 4 August 1998
202 Guemesand Wright
m.
Vortex v.
n.
FIG 1. New inferior oblique insertion line is parallel to inferior rectus muscle axis. FI6 3. Inferior oblique and inferior rectus muscle seen from below. Different locations for inferior oblique reinsertion. Inferior obliqt
Neurofibrov bundl
FIG 2. Posterior fibers of inferior oblique muscle are anteriorized, creating "J" deformity.
cle for primary inferior oblique overaction, inferior oblique overaction associated with DVD, and unilateral congenital superior oblique palsy. All patients were operated by a single surgeon (K.W.) between August 1994 and June 1996. Exclusion criteria included previous inferior oblique surgery, infraplacement or supraplacement of the horizontal rectus muscles, or previous vertical muscle operation. Twenty-one patients (37 eyes) were included in the study. There were 13 boys and 8 girls, with ages ranging from 18 months to 9.5 years (mean 4.76 years).
Follow-up ranged from 3 to 12 months (mean 5.3 months). Fourteen patients had primary inferior oblique overaction, 10 patients with esotropia and 4 patients with exotropia. Four patients had DVD associated with inferior oblique overaction. Three patients had unilateral congenital superior oblique palsy with secondary inferior oblique overaction (Table 1). Three patients had symmetric, 14 patients had asymmetric, and 4 patients had unilateral graded anterior transposition. Fifteen patients also had simultaneous horizontal muscle surgery. Ocular motility examination included visual acuity, ductions, versions, and ocular deviation in primary position measured by alternate prism cover test. The presence of a significant V pattern (> 15 PD) was clinically observed and noted; however, it was not quantitated by prism cover testing in all children. Versions were graded preoperatively and postoperatively on a scale o f - 4 underaction to +4 overaction, with 0 being normal. When versions were checked, the adducting eye was partially covered to ensure fixation with the abducting eye. Vertical deviation in primary position was measured with alternate cover testing to disclose the full phoria. When a DVD was present, a base down prism and cover was placed over the eye to be measured. The cover was switched to the fixing eye, and the amount of base down prism was increased until no downward movement was seen under the eye behind the prism. Care was taken to distinguish DVD from a true hypertropia. The results of last examination were recorded for the study. The surgical technique has been previously described; it
Journal of AAPOS Volume 2 Number 4 August 1998
Guemes and Wright 203
TABLE 1. Diagnosis in 21 patients with graded anteriorizationof inferior oblique muscle
Primary inferior oblique overaction
No. of patients
Esotropia
Exotropia
11
3
Inferior Superior oblique oblique overaction palsy +DVD 3
4
consisted of moving the inferior oblique insertion to a location along the temporal border of the inferior rectus muscle. 8 T h e anterior transposition was classified by its relationship to the inferior rectus insertion (ie, at the inferior rectus insertion), 1 mm posterior, 2 mm posterior, 3 mm posterior, 4 mm posterior, or 4 mm posterior and 2 mm temporal (Figure 3). In all cases the new inferior oblique insertion line was oriented parallel to the inferior rectus muscle axis so there was no "J" deformity. Placement of the inferior oblique was based on the severity of the overaction. The more the inferior oblique overacted, the more anterior the placement of the new insertion. V patterns and vertical deviations in primary position also influenced the amount of anterior transposition. For mild inferior oblique overaction, if it were associated with a significant V pattern, the new insertion was placed 4 mm posterior and 2 mm temporal or 4 mm posterior to the inferior rectus insertion. For moderate inferior oblique overaction, the new insertion was placed 3 mm posterior to the inferior rectus insertion. For severe inferior oblique overaction or inferior oblique overaction associated with DVD, the new insertion was placed 2 to 1 mm posterior to the inferior rectus insertion or at the temporal border of the inferior rectus insertion (except 1 eye with mild DVD).
RESULTS Versions
Thirty-seven eyes underwent graded anterior transposition, of which 11 (33%) had +3 or more overaction (Table 2). Postoperatively all eyes had no more than plus or minus 1 oblique dysfunction, and 33 of 37 eyes (89%) showed normal versions. The 11 eyes with +3 or more overaction received graded anterior transposition 2 mm posterior to the inferior rectus insertion to full anterior transposition. N o n e of these patients showed more than _+1 inferior oblique dysfunction after surgery, with 9 of 11 patients showing normal versions. N o patient had clinically significant limited elevation after surgery. This included 5 patients who underwent unilateral surgery, 2 patients at 1 mm posterior, 2 patients at 2 mm, and 1 patient at 4 mm posterior to the inferior rectus insertion. The amount of graded anterior transposition positively correlated with the degree of change in version, with the larger the anterior transposition the greater the change in versions. The correlation coefficient for anterior transposition and version was -0.60, P < .001 (Spearman's rank).
TABLE 2. Version changes in 37 eyes of 21 patients undergoing graded anteriorizationof inferior oblique muscle, by degree of anteriorization.
Version Patient Preoperative post- Version Anteriorization No Eye versions operative change Full
1 2 1 mm posterior 3 4 5 6 6 7 1 2 mm posterior 8 8 9 7 10 11 12 13 13 3 mm posterior 14 15 4 2 4 mm posterior 14 15 16 16 17 17 18 10 19 20 20 21 21 4 mm posterior, 9 2 mm temporal 18 OD, Righteye;OS, left eye.
OD OS OS OS OD OD OS OD OS OD OS OS OS OD OD 0D OD OS OS 0S OD OD OD OD OD OS OD OS 0S OS OD OD OS OS OD OD OD
+3 +2.5 +2.5 +3 +3 +3 +3 +3 +3 +3 +3 +2 +2.5 +2.5 +2 +2.5 +4 +3 +2.5 +1,5 +2 +1.5 +2 +1 +2 +2 +2 +2 +0.5 +1 +1 +1 +0.5 +2 +2 +1 +1.5
Normal Normal Normal Normal Normal +1 +1 Normal Normal Normal Normal Normal Normal Normal -1 Normal Normal Normal Normal Normal Normal -1 Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal Normal
3 2.5 2.5 3 3 2 2 3 3 3 3 2 2.5 2.5 3 2.5 4 3 2.5 1.5 2 2.5 2 1 2 2 2 2 0.5 1 1 1 0.5 2 2 1 1.5
A clinically evident "V" pattern was present preoperatively in patients with bilateral primary inferior oblique overaction. Postoperatively the pattern resolved, noted by clinical observation. None of the 3 patients with unilateral superior oblique palsy had a significant V pattern. Vertical Alignment Eleven patients (15 eyes) had a vertical deviation in primary position 4 PD or more (Table 3). Three patients with unilateral congenital superior oblique palsy had unilateral graded anterior transposition of 1 ram, 2 mm, and 3 mm posterior to the inferior rectus insertion for preoperative hypertropias of 20 PD. For more than +2 inferior oblique overaction, the new insertion was placed 2 to 1 mm posterior to the inferior rectus insertion; for milder overaction,
Journal ofAAPOS Volume 2 Number 4 August 1998
204 Guemesand Wright ]'ABLE3. Patientswith true hypertropia_>4PD associatedwith asymmetricor unilateral inferior oblique overaction
Primary position Patient No.
Diagnosis
Anteriorization posterior to inferior rectus insertion (mm)
Pre (PD)
Post(PD)
Change (PD)
Unilateral surgery
3 SOP OD 1 posterior RHT 20 Ortho 20 5 XT + V + amblyopia OD 1 posterior RHT 6 Ortho 6 11 SOP OD 3 posterior RHT 20 RHT 5 15 12 SOP OD 0.2 posterior RHT 20 RHT 2 18 Asymmetric surgery 7 ET + IOOA OD 1.0 posterior, OS 2.0 posterior RHT 4 Ortho 4 9 ET + IOOA OD 4 posterior 2 temporal, OS 2.0 posterior RHT 6 Ortho 6 10 ET + IOOA OD 2.0 posterior, OS 4.0 posterior RHT 6 Ortho 6 Pre, Preoperative;Post, postoperative;SOP,superiorobliquepalsy;OD, right eye;RHT,right hypertropia;Ortho, orthotropia;XT,exotropia, V,,"V" pattern;ET,esotropia.
TABLE 4. Gradedanteriorizationfor patients with DVD and associated inferior oblique overaction
Primary position Patient No.
Diagnosis
1
ET + DVD + IOOA
2
ET + DVD + IOOA
6
ET+ DVD + IOOA
13
ET + DVD + IOOA
Anteriorization posterior to inferior rectus insertion (mm) OD full OS 1.0 posterior OD 3 posterior OS full OS 1.0 posterior OS 1.0 posterior OD 2.0 posterior
OS 2.0 posterior Pre, Preoperative;Post, postoperative;ET,esotropia,OD, righteye;Ortho, orthotropia;OS, left eye.
the new insertion was placed 3 mm posterior to the inferior rectus insertion. Postoperatively, the anterior transposition changed the vertical deviation by 20 PD for 1 ram, 18 PD for 2 ram, and 15 PD for 3 mm anterior transposition (mean 18 PD). This resulted in good postoperative alignment in primary position, with 1 patient orthophoric, 1 patient with a right hypertropia of 4 PD, and 1 patient with a right hypertropia of 5 PD. One patient with exotropia, +3 primary inferior oblique overaction, and dense amblyopia had a unilateral anterior transposition of 1 mm posterior to the inferior rectus insertion. The vertical deviation in this patient was variable and measured approximately 6 PD preoperatively, and postoperatively there was no significant vertical deviation. Three patients with asymmetric primary inferior oblique overaction and a true hypertropia of 4 PD to 6 PD in primary position had asymmetric graded anterior transposition. Postoperatively the vertical deviation was eliminated in all patients, with a mean change of 5 PD. Four patients had bilateral surgery for primary inferior oblique overaction associated with DVD (range per patient 6 to t5 PD). All patients had a significant improvement after surgery (Table 4). Two patients showed no appreciable DVD with 6 to 10 PD improvement, and 2 patients had a small residual DVD (4 and 5 PD) with 7 and 10 PD improvement.
Pre (PD)
Post (PD)
Change (PD)
OD DVD 10 OS DVD 8 OD DVD 5 OS DVD 15 OS DVD 10 OS DVD 12 OD DVD 6
Ortho Ortho DVD 4 DVD 5 DVD 5 DVD 5 Ortho
10 8 1 10 5 7 6
OS DVD 3
Ortho
3
DISCUSSION Historically, severe inferior oblique overaction has been difficult to manage with procedures such as inferior oblique recession and myectomy.2, 3 More "powerful" procedures such as extirpation, denervation, and anterior transposition are effective in reducing overaction, but these procedures can result in inferior oblique underaction. 3-5 This is especially problematic for unilateral anterior transposition procedures, where the complication of postoperative limitation of elevation with a hypotropia in primary position is common. 5 In the current study we found the graded anterior transposition avoided the complication of postoperative limited elevation yet was effective in correcting both mild and severe inferior oblique overaction. Eleven eyes with +3 or more overaction had full anterior transposition to 2 mm posterior to the inferior rectus insertion. Postoperatively, all these severe cases showed no more than +1 oblique dysfunction, and 9 of the 11 eyes (82%) showed normal versions. It was reassuring to find that none of our patients had significant limitation of elevation or a hypotropia in primary position postoperatively. This included 3 patients who underwent large unilateral anterior transpositions of 1 mm, 2 mm, and 3 mm posterior to the inferior rectus insertion. We attribute the success of our graded anterior trans-
Journal of AAPOS Volume 2 Number 4 August 1998
positions to 4 factors. First, the amount of anterior transposition is tailored to the amount of inferior oblique overaction. Moving the inferior oblique insertion anterior to the equator, toward the inferior rectus insertion, progressively reduces the elevator function of the inferior oblique muscle. 4 Eyes with larger amounts of inferior oblique overaction receive larger anterior transpositions. In patients with minimal inferior oblique overaction it is not necessary to perform a full anterior transposition because this may result in limited elevation postoperatively. In these patients the inferior oblique muscle is only minimally anteriorized to 4 mm posterior to the inferior rectus insertion. The second factor is to place the new inferior oblique insertion perpendicular to the inferior rectus muscle to avoid anteriorizing the posterior muscle fibers (Figure 2). In contrast, if the new insertion is oriented parallel to the inferior rectus insertion, this tightens the posterior muscle fibers, creating a "J" deformity of the inferior oblique muscle (Figure 1). Stager et al 6 and Stidham et al 7 have shown the importance of the posterior muscle fibers and the neurovascular bundle in producing limited elevation after inferior oblique anterior transposition. The exact mechanism remains unknown, but anteriorizing the posterior fibers of the inferior oblique muscle probably tightens the neurovascular bundle and creates an active leash that pulls the eye downward on attempted elevation. 7 Our anterior transposition procedure avoids the "J" deformity by always keeping the posterior muscle fibers at least 3 mm posterior to the inferior rectus insertion (Figure 3). Third, it is important to avoid inadvertent resection of the inferior oblique muscle when securing the muscle with suture. If sutures are placed more than 3 mm proximal to the inferior oblique tendon, this will significantly shorten the inferior oblique muscle, creating restriction in elevation. Clear exposure of the inferior oblique insertion is essential to safely remove the inferior oblique muscle close to the sclera without a significant resection. The other important factor was that we do not replace the inferior oblique muscle anterior to the inferior rectus insertion. In patients with DVD and inferior oblique overaction the most we would anteriorize the inferior oblique muscle was to the inferior rectus insertion, not anterior to the insertion. Others have advocated anteriorizing the inferior oblique anterior to the inferior rectus insertion 9, 10; however, our experience is that this leads to limited elevation and is not necessary for most cases of DVD associated with inferior oblique overaction. We also found the graded inferior oblique anterior transposition procedure to be useful in patients with unilateral congenital superior oblique palsy and large vertical deviations in primary position. 11, 12 Three of our patients with unilateral congenital superior oblique palsy underwent an anterior transposition procedure of 1 to 3 mm posterior to the inferior rectus insertion for vertical deviation in primary position between 15 and 20 PD. This uni-
Guemes and Wright 205 lateral anterior transposition procedure resulted in a mean reduction in the vertical deviation of 18 PD, and in all 3 patients the postoperative residual deviation was less than 5 PD. Despite this large change in vertical deviation, only 1 of the 3 patients showed a -1 limitation to elevation in adduction (trace inferior oblique underaction). In contrast to the unilateral anterior transposition procedure, the asymmetric bilateral anterior transposition procedure did not result in large changes in the vertical deviation. Of 3 patients with bilateral asymmetric surgery for asymmetric inferior oblique overaction and a true hypertropia, the eye with the hypertropia would receive the stronger procedure (inferior oblique placed more anterior) than the fellow eye. Asymmetric anterior transposition of no more than 2 mm did reduce the vertical deviation but no more than 6 PD. Our results show that we should not expect asymmetric graded anteriorization of less than 2 mm to eliminate true vertical deviations of more than 6 PD. If the deviation in primary position is greater than 6 PD, consider adding a vertical rectus muscle to the surgical plan. Fortunately, it is unusual that patients with bilateral asymmetric inferior oblique overaction have large vertical deviations; therefore the asymmetric procedure usually is sufficient. For the treatment of DVD, previous reports have suggested a full anterior transposition procedure, even placing the new inferior oblique insertion anterior to the inferior rectus insertion. 9, 10 We used our graded anterior transposition procedure, limiting the anterior transposition to the inferior rectus insertion and keeping the new insertion parallel with the inferior rectus muscle axis. Despite this potentially less potent procedure, our results with DVD were good. Of 4 patients with bilateral DVD ranging between 10 PD and 15 PD in the worse eye, postoperatively 2 patients had no appreciable DVD and the other 2 patients had less than 5 PD of residual DVD. The mean improvement in DVD in these patients was 10 PD. We found that relatively large anterior transpositions were needed to correct DVD, but it was not necessary to move the inferior oblique anterior to the inferior rectus insertion. In patients with asymmetric DVD we performed an asymmetric anterior transposition procedure. Others have recommended graded inferior oblique recessions and anterior transpositions. 2, 13-15 The graded inferior oblique muscle recession is actually an anteriorization procedure because the new insertion site is significantly anterior to the original insertion, which is at the macula a few millimeters from the optic nerve. Parks' 10 mm inferior oblique recession, which is marked 3 mm posterior and 2 mm temporal to the temporal pole of the inferior rectus insertion, is, in fact, an anterior transposition procedure, is Apt and Call 14 recommended many different insertion sites, and these were a form of anterior transposition. Kratz et al9 graded the amount of anterior transposition of the posterior fibers of the inferior oblique muscle for DVD associated with inferior oblique overaction. Posterior fibers in the inferior oblique were inserted at 3
Journal of AAPOS Volume 2 Number 4 August 1998
206 Guemesand Wright different stations depending on the severity of the D V D . W e realize and respect that there are m a n y valid approaches to correcting inferior oblique overaction. O n the basis of data f r o m this study and our clinical experience, we suggest the following system o f graded anterior transposition of the inferior oblique. Primary inferior oblique overaction (IOOA) • I O O A versions +4 = full anterior transposition* (no "S" deformity) +3 = 1 m m posterior inferior rectus insertion +2 = 3 or 4 m m posterior inferior rectus insertion + 1 = 4 m m posterior inferior rectus insertion and 2 m m temporal to inferior rectus • Bilateral asymmetric p r i m a r y I O O A with hypertropia 5 to 6 P D = asymmetric anterior transposition at least 2 m m difference between fellow eyes DVD with IOOA • D V D : 10 to 15 P D = full anterior transposition (no "J" deformity) 4 to 10 P D = 1 to 2 m m posterior inferior rectus insertion Unilateral Congenital Superior Oblique Palsy • H y p e r t r o p i a in p r i m a r y position 15 to 20 P D with +3 I O O A = ipsilateral anterior transposition 1 to 2 m m posterior inferior rectus insertion
*Avoid unilateral full anterior transposition to avoid postoperative limitations of elevation.
@
References
1. Wright KW. Current approaches to inferior oblique muscle surgery. In: Hoyt CS, editor. Focal points 1986: clinical modules for ophthalmologists. San Francisco: American Academy of Ophthalmology; 1986. Vol 4, module 6. 2. Parks MM. The weakening surgical procedures for eliminating overaction of the inferior oblique muscle. Am J Ophthatmol 1972;73:107-22. 3. Del Monte MA, Parks MM. Denervation and extirpation of the inferior oblique: an improved weakening procedure for marked overaction. Ophthalmology 1983,90;1178-83. 4. Elliot RL, Nankin SJ. Anterior transposition of the inferior oblique. J Pediatr Ophthalmol Strabismus 1981;18:35-8. 5. Bremer DL, Rogers GL, Quick LD. Primary-position hypotropia after anterior transposition of the inferior oblique. Arch Ophthalmol
1986;t04:229-32. 6. Stager DR, Wealdey DR, Stager D. Anterior transposition of the inferior oblique: anatomic assessment of the neurovascular bundle. Arch Ophthalmol 1992;110:360-2. 7. Stidham DB, Stager DR, Kamm KE, Grange RW. Stiffness of the inferior oblique neurofibrovascular bundle. Invest Ophthalmol Vis Sci 1997;38:1314-20. 8. Wright KW. Inferior oblique surgery. In: Wright KW, editor. Color atlas of ophthalmic surgery, strabismus. Philadelphia: JB Lippincott; 1991. p. 173-99. 9. Kratz RE, Rogers GL, Bremer DL, Leguire LE. Anterior tendon displacement of the inferior oblique for DVD. J Pediatr Ophthalmol Strabismus 1989;26:212-7. 10. Mims JL, Wood RC. Bilateral anterior transposition of the inferior obliques. Arch Ophthalmol 1989:107:41-4. 11. Gonzalez C, Cinciprini C. Anterior transposition of the inferior oblique in the treatment of unilateral superior oblique palsy. J Pediatr Ophthalmol Strabismus 1995;32:107-13. 12. May MM, Beauchamp GR, Price RL. Recession and anterior transposition of the inferior oblique for treatment of superior oblique palsy. Graefes Arch Clin Exp Ophthalmol 1988;226:407-9. 13. Fink WH. Surgery of the vertical muscles of the eye. Springfield (IL): Charles C Thomas; 1962. 14. Apt L, Call NB. Inferior oblique muscle recession. AmJ Ophthalmol 1978;85:95-100. 15. Parks MM. Atlas of strabismus surgery. New York: Harper & Row; 1983.
An Eye on the Arts T h e Arts on the Eye
"You have given up [the town of] Bradfield altogether then?" "Too provincial m y boy! What's the good of a village practice with a miserable three thousand or so a year for a m a n that wants r o o m to s p r e a d ? . . . I've taken to the eye, m y boy. T h e r e ' s a fortune in the eye. A m a n grudges a halfcrown to cure his chest or his throat, but h e ' d spend his last dollar over his eye. T h e r e ' s m o n e y in ears, but the eye is a gold mine!" - - S i r Arthur C o n a n D o y l e (from The Stark Muno Letters)