Journal of Neuro-Ophthalmology, June 2001, Volume 21, Issue 2

The Effect of Lid Elevation on the Cross-Cover Test

OBJECTIVE: To discern the effect of manual lid elevation on muscle balance using the cross-cover test. MATERIALS AND METHODS: One hundred consecutive patients who were orthophoric in all fields of gaze were prospectively studied. A repeat cross-cover test was performed with the eyes looking down and to either side while pulling the lid ipsilateral to the abducting eye up and to either side. The presence and type of any phoria was noted. RESULTS: Eighty-four percent of patients and 76% of eyes developed a phoria with lifting a lid. Vertical phorias developed in 79 patients and 136 eyes, whereas horizontal phorias were seen in 51 patients and 83 eyes. In all but one case, the vertical deviation was a hyperphoria ipsilateral to the elevated lid. Horizontal deviations were esophoric in 63 eyes of 39 subjects. Induced phorias were most commonly symmetric from side to side. CONCLUSIONS: Lifting the lid produces an iatrogenic phoria that mimics a skew or IV nerve paresis. We hypothesize that stretching the lid causes traction on the levator-superior rectus complex, thereby increasing its tone. Although it makes testing more difficult, we recommend that the lids not be manipulated while performing phoria testing.

Journal of Neuro- Ophthalmology 21( 2): 87- 89, 2001. © 2001 Lippincott Williams & Wilkins, Inc., Philadelphia The Effect of Lid Elevation on the Cross- Cover Test Michael L. Rosenberg, MD, and Martin S. Gizzi, MD, PhD Objective: To discern the effect of manual lid elevation on muscle balance using the cross- cover test. Materials and Methods: One hundred consecutive patients who were orthophoric in all fields of gaze were prospectively studied. A repeat cross- cover test was performed with the eyes looking down and to either side while pulling the lid ipsilateral to the abducting eye up and to either side. The presence and type of any phoria was noted. Results: Eighty- four percent of patients and 76% of eyes de­veloped a phoria with lifting a lid. Vertical phorias developed in 79 patients and 136 eyes, whereas horizontal phorias were seen in 51 patients and 83 eyes. In all but one case, the vertical deviation was a hyperphoria ipsilateral to the elevated lid. Hori­zontal deviations were esophoric in 63 eyes of 39 subjects. Induced phorias were most commonly symmetric from side to side. Conclusions: Lifting the lid produces an iatrogenic phoria that mimics a skew or IV nerve paresis. We hypothesize that stretching the lid causes traction on the levator- superior rectus complex, thereby increasing its tone. Although it makes testing more difficult, we recommend that the lids not be manipulated while performing phoria testing. Key Words: Strabismus- Phoria- Lids- Cross- cover. Measuring phorias with a cross- cover test in all fields of gaze is a technique that is crucial to the evaluation and follow- up of patients with ocular motility disorders. For ophthalmologists in particular, the diagnosis of a subtle IV nerve palsy or skew deviation is most often made on the basis of such measurements. Ocular refixation move­ments by patients with relatively low lids can be difficult to see, especially when the eyes are infraducted and ab­ducted. It has been our routine practice to lift the lids in order to better see the movements of the eyes in this position. We noted that, in some patients, this technique affected the measured muscle balance. We prospectively investigated the incidence of this phenomenon in a series of patients with no significant phoria on routine testing Manuscript received September 12, 2000; accepted February 12, 2001. From Seton Hall University, Department of Neuroscience, New Jer­sey Neuroscience Institute, Edison, New Jersey. Address correspondence and reprint requests to Michael L. Rosenberg, MD, Director of Neuro- Ophthalmology, Professor of Neu­rology, Seton Hall University, Department of Neuroscience, New Jer­sey Neuroscience Institute, JFK Medical Center, 65 James Street, Edi­son, NJ 08818; e- mail: mrosenberg@ solarishs. org. by rechecking the cross- cover test with the lid elevated. We also examined whether the direction of lid manipu­lation affected the change. METHODS All patients in the neuro- ophthalmology clinic are rou­tinely tested with a cross- cover test in all positions of gaze. For this study, we excluded patients with any his­tory or physical examination finding suggestive of a pro­cess that could cause an extraocular muscle problem. One hundred consecutive patients with no significant phoria when looking down and to either side during rou­tine cross- cover testing were further tested while the lids were manipulated. While the patient looked down and to the side, the lid of the abducted eye was gently pulled up, and then up and laterally as well as up and medially. The type of any phoria was noted in each of these positions. Testing was then repeated while the subject fixated down and to the opposite side. Care was taken to pull gently on the lid and to ensure that no external pressure was placed on the globe. Measurements were not routinely made because of the difficulties of lifting the lid and trying to manipu­late a prism bar with one hand and move a paddle for the cross- cover test with the other hand at the same time. RESULTS Phorias developed in a striking percentage of patients. Eighty- four patients and 76% of eyes developed a phoria with lifting of the lids in at least one direction. Vertical phorias were more common and developed in 79 patients and 136 eyes, whereas horizontal phorias were induced in 51 patients and 83 eyes. In all but one case, the vertical deviation was a hyperphoria ipsilateral to the elevated lid. Four patients had the vertical phoria measured. One patient measured 2 diopters, whereas the other three pa­tients measured 4 diopters. The horizontal deviations were mostly esophorias ( 63 eyes in 39 subjects) with only 13 subjects ( 21 eyes) showing an exophoria. The horizontal phorias did not appear to be secondary to pas­sive movement of the globe as the same effect was often observed ( e. g., esophoria) no matter which direction one pulled the lid. 87 88 M. L. ROSENBERG AND M. S. GIZZI TABLE 1. Phorias and lid elevation Eyes down and RT Eyes down and LT Patient 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 Lid up & RT H H H HE O H H HX O H HX O HX O O E H H O H X H HX H H H H X H O O H HE HE O H H O H O E H H O O H H H H H O O H HE H O O O O H H H O O H O Lid up O HT H HE O O O H O O O O HX O O O HE H O O H H O O H H H O H O O H HE HE O H H O H O HE H O O O H O H H H O O H H HE O O O O O E H O HE O O Lid up & LT O O H HE O O O H O O O HE HX O O E HE HE O O O H O O H HE H O O O O O O HE O HE O O O O E H O O O HE O O HE HE O O O O HE H O O H O E H E H O O Lid up & LT H H H E Hypo, X H O HX H O HX O HX H O E H H O H X H HX H HE H HE X O H O H O HE H H O O O O E H H O H H H H H H H O H E H O H O O O H H H HE H O Lid up O O H E O O H H H O O O HX H O O HE H O O H H O O H H E O H H O O O HE H H H O HE O E H O O H H HE H H H H O H O HE O H O O O E H HE HE O O Lid up & RT O O H E O O H HE O H O O HX H O E HE HE O O O H O O E H E O H H O O O HE H HE H O HE O E HE O O HX HE E HE E HE X O H O HE H O O H O E HE HE O E O TABLE 1. Continued Eyes down and RT Eyes down and LT Patient 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 93 94 95 96 97 98 99 100 Lid up & RT H O H H H HX E H O O H O HE O O E X O H H O H HE O O O E E H H HX O H O O Lid up H O H H HE H E HE O O H O O O O E X O H O O H H O O O E E H H HX H H H O Lid up & LT H O E H E O E HE O H H O O O O E X O o o o E H O O O E E H E HX O H O O Lid up & LT H O H H H O HE H O O H O HE X O E H O H H O H E H H HE O O H H HX O H O O Lid up H O H H HE H HE HE O O H O O X O E H O H O O HE E H H HE O O H H HX O H H O Lid up & RT H O E H HE HX HE HE O H H O O XH O E H O H O O HE E H E HE E E H H HX O H O O * The patient number is in the first column. The next three columns show the results of cross- cover testing while the subject is looking down and to the right ( RT) with the lid pulled up and to the right, straight up, then up and to the left ( LT). The last three columns are the cross- cover findings while the subject is looking down and to the left with the lid lifted up and to the left, straight up, then up and to the right. E, eso; H, hyperphoria ipsilateral to the abducting eye; O, ortho; X, exo. Direction of lid elevation influenced the incidence and type of phoria seen. Fifty- four eyes had a vertical phoria with the lid pulled up and out but not up and in, com­pared with 14 eyes with a vertical phoria while the lid was pulled up and in but not up and out. Horizontal phorias had the reverse pattern. Eleven patients ( 16 eyes) had phorias with the lid up and out and not up and in as opposed to 40 eyes ( 27 subjects) with a phoria brought out with the lids pulled up and in. Fifty- four of the patients developed vertical phorias that were the same on right and left gaze, whereas 77 patients had symmetrical horizontal patterns. Forty-six patients were symmetric for horizontal and verti­cal phorias. DISCUSSION During the past decade, much has been learned regard­ing the physical structure of the soft tissues in the orbit / Neuro- Ophthalmol, Vol. 21, No. 2, 2001 HYPERDEVIATIONS WITH MANUAL LID ELEVATION 89 and on the function of the extraocular muscles. It is now clear that there is an extensive system of smooth muscle and fibroelastic tissue that serves to stabilize the relative position of the muscles with the globe ( 1- 3). This system in turn maintains the same direction of action of the muscle no matter where the eye is in the orbit. Elevating the lid in 84% of patients had an effect on extraocular muscle tone, manifested by a marked change in muscle balance. We initially suspected that the eye was being pulled in a specific direction off of the visual axis; however, this suspicion did not explain an unchang­ing horizontal phoria irrespective of the direction of lid pull. Obviously, this suspicion was also not the explana­tion in the patient who developed a hypophoria ipsilat-eral to the elevated lid. It seems more likely that pulling on the lid changed the relative tone of the vertical and horizontal recti by changing the position of the fibroelas­tic pulleys. Because different subjects have different de­grees of laxity in the pulley system and in the soft tissue attaching the lid to it, it is not surprising that lifting the lid had different effects in different subjects. Clinically, this variance among patients has made a substantial difference in our approach to measuring pho-rias. The typical deviation appears to be four diopters, and this deviation was easily visible. The pattern of the iatrogenic deviation mimicked an inferior rectus weak­ness. Unfortunately, most patients with skews manifest the abnormality in the same pattern. Thus, many patients thought to have a skew deviation with cross- cover may have been misdiagnosed. Anyone doing cross- cover tests in all fields of gaze should be wary of this effect and test all patients without manipulating the lids. REFERENCES 1. Demer JL, Poukens V, Miller JM, et al. Evidence for fibromuscular pulleys of the recti extraocular muscles. Invest Ophthalmol Vis Sci 1995; 36: 1125- 36. 2. Demer JL, Poukens V, Miller JM, et al. Innervation of extraocular pulley smooth muscle in monkeys and humans. Invest Ophthalmol Vis Sci 1997; 38: 1774- 85. 3. Porter JD, Poukens V, Baker RS, et al. Structure- function corre­lations in the human medial rectus extraocular muscle pulleys. Invest Ophthalmol Vis Sci 1996; 37: 468- 72. J Neuro- Ophthalmol, Vol. 21, No. 2, 2001