1040-5488/02/7903-0151/0 VOL. 79, NO. 3, PP. 151 157 OPTOMETRY AND VISION SCIENCE Copyright 2002 Americn Acdemy of Optometry ORIGINAL ARTICLE A Survey of Modlities for Convergence Insufficiency MITCHELL SCHEIMAN, OD, FAAO, JEFFREY COOPER, MS, OD, FAAO, G. LYNN MITCHELL, MAS, PAUL DE LAND, PhD, SUSAN COTTER, OD, FAAO, ERIC BORSTING, OD, MS, FAAO, RICHARD LONDON, OD, MA, FAAO, nd MICHAEL ROUSE, OD, MS, FAAO Pennsylvni College of Optometry, Phildelphi, Pennsylvni (MS), Stte College of Optometry, Stte University of New York, New York, New York (JC), The Ohio Stte University, College of Optometry, Columbus, Ohio (GLM), Cliforni Stte University, Fullerton, Deprtment of Mthemtics, Fullerton, Cliforni (PDL), Southern Cliforni College of Optometry, Fullerton, Cliforni (SC, EB, MR), Pcific University College of Optometry, Pcific Grove, Oregon (RL) ABSTRACT: Bckground. Convergence insufficiency (CI) is common nd distinct binoculr vision disorder. However, there is lck of consensus regrding the tretment most pproprite for CI. Possible tretment modlities include bse-in prism, pencil pushup therpy (PPT), reding glsses, home-bsed vision therpy/orthoptics (HBVT), nd office-bsed vision therpy/orthoptics (OBVT). The purpose of this study ws to investigte the cre process for CI by surveying eyecre professionls regrding the most common tretment modlities used by both optometrists nd ophthlmologists cross the United Sttes. Methods. Surveys requesting doctors to indicte which tretment(s) they prescribed nd believed to be most effective for symptomtic CI ptients were miled to 863 optometrists nd 863 ophthlmologists in the United Sttes. Results. Fifty-eight percent of the optometrists responded to the survey; the most common tretment prescribed ws PPT (36%) followed by HBVT (22%) nd OBVT (16%). For the ophthlmologists (who hd 23% response rte), the most common tretment prescribed ws PPT (50%) followed by HBVT (21%) nd bse-in prism (10%). Conclusions. This survey suggests tht most eyecre prctitioners prescribe PPT s the initil tretment for CI. (Optom Vis Sci 2002;79:151 157) Key Words: convergence insufficiency, survey, binoculr vision disorder, vision therpy, orthoptics, exotropi, pencil push-ups Convergence insufficiency (CI) is common nd distinct binoculr vision disorder with reported prevlence of 2.25% to 8.3% mong children nd dults in the United Sttes. 1 4 Common symptoms include diplopi, sthenopi, hedches, nd blurred vision during ctivities tht require close vision (e.g., reding, computer viewing, or desk work). 5 13 The exct impct of symptomtic CI on n individul s performnce t school or work, nd on qulity of life is unknown. Clinicl signs of CI include exophori tht is greter t ner thn t distnce, receded ner point of convergence, nd reduced positive fusionl vergence t ner. 6 There is lck of consensus regrding the most pproprite tretment for CI. Vrious tretment modlities hve been described nd include bse-in prism, pencil pushup therpy (PPT), reding glsses, home-bsed vision therpy/orthoptics (HBVT), nd office-bsed vision therpy/orthoptics (OBVT). 14 28 Only OBVT hs been extensively evluted. Cooper nd Duckmn 5 (nd lter Grishm 29 ) reviewed the literture for the yers 1940 to 1987 nd summrized 17 studies tht included 2149 ptients. They clculted weighted cure rte of 78%, n improved rte of 15%, nd filure rte of 5%. The combined improved nd cured rte ws 93%. Some of these studies hve been criticized becuse they did not clerly define the CI popultions treted nd becuse they were retrospective nd uncontrolled. There hve been few prospective, double-blind studies tht hve shown vergence therpy to decrese symptoms nd to improve fusionl vergence mplitudes in CI ptients. 14 16 However, the well-controlled, double-blind studies tht exist hve hd smll number of subjects nd thus limited sttisticl power. Another populr tretment consists of home-bsed therpy using PPT to develop incresed totl convergence mplitudes. Although PPT is believed to be tretment commonly prescribed by clinicins, there hs been only one clinicl study evluting its efficcy. Gllwy et l. 30 conducted pilot study to investigte the
152 Modlities for Convergence Insufficiency Scheimn et l. effectiveness of PPT s tretment for CI. Only four of the 12 CI ptients demonstrted enough of n improvement in both ner point of convergence nd positive fusionl vergence to be clssified s norml. All but one subject experienced n improvement in symptoms from PPT, lthough only one subject reported totl elimintion of symptoms. Less thn 50% of subjects completed the study, which suggests there ws problem with complince. Bse-in relieving prisms hve lso been dvocted s n pproprite tretment for CI. Prisms decrese the lod on the vergence system nd my be dvntgeous becuse they require minimum of time from both the ptient nd the doctor. A potentil problem with prisms is tht the mount of prism pproprite for ner my be inpproprite for distnce, thereby necessitting two pir of glsses for the ptient. Worrell et l. 31 prescribed two pir of glsses to symptomtic ptients with binoculr vision disorders; one set of eyeglsses included prism bsed on Sherd s criterion nd the other set of eyeglsses hd no prism. were sked to wer ech set of glsses for period of time nd to select the one they preferred. with esophori preferred the glsses with prism. In ptients with exophori, only presbyopic exophores wering bifocls t ner preferred the prism glsses. Long-term preference for either pir of glsses ws not evluted. Mein nd Hrcourt 32 suggested tht bse-in prism ws effective for elderly ptients who could not ttend orthoptic therpy visits or for ptients in whom orthoptics hd not been successful. Lie nd Opheim 33 re strong dvoctes for the use of prisms for CI. They prescribed prisms for 46 subjects (36 of whom hd CI) nd reported tht symptoms were reduced nd bsic clinicl findings were improved in ll subjects. Becuse symptomtic CI is common problem tht is treted with vrious tretment modlities, it is importnt to determine the mode of tretment most commonly prescribed by the ophthlmic community. Previously, Chin et l. 34 surveyed 300 optometrists in the Sn Frncisco By re to determine their primry mode of tretment for CI. One hundred six (35.3%) optometrists responded to the survey. The two most commonly recommended tretments were PPT (34%) nd OBVT (22%). Approximtely 20% of the optometrists prescribed bse-in prism, 18% referred the ptient to nother prctitioner, nd 6% did not recommend ny tretment. Becuse this survey evluted the current tretment strtegies of optometrists in the Sn Frncisco By re only, it is difficult to generlize this study to the rest of the country since tretment my vry from region to region. In ddition, the survey did not evlute the tretment ptterns of ophthlmologists. The purpose of our study ws to investigte the cre process for CI nd the most common tretment modlities used by both optometrists nd ophthlmologists cross the United Sttes. METHODS Miling lists for optometrists were obtined from the Americn Optometric Assocition (AOA) nd, for ophthlmologists, from the Officil Americn Bord of Medicl Specilties Directory of Bord Certified Medicl Specilists. The ophthlmologic list llowed us to identify both generl nd peditric ophthlmologists. All other subspecilties in ophthlmology were eliminted. Both the optometric nd ophthlmologic lists were rrnged by zip code. Using these ordered lists, systemtic smple ws drwn by selecting every kth subject from the list. The smpling increment, k, ws selected so tht the number of subjects smpled would be pproximtely 800. For exmple, the AOA list contined slightly more thn 16,000 nmes, so k 16000/800 20 ws used to select the smple of optometrists. We ctully miled 863 surveys to optometrists nd 863 surveys to ophthlmologists. By rrnging the lists by zip code, we ttempted to ensure the selection of doctors from ll prts of the U.S. The smple size ws selected ssuming 50% response rte. With such response rte, we expected 400 returned surveys per group, llowing us to construct 95% confidence intervl for the proportion responding in prticulr fshion with 0.05 mrgin of error. Humn subjects pprovl ws obtined from the Pennsylvni College of Optometry nd the Stte University of New York, Stte College of Optometry Institutionl Review Bords. The survey included cover letter describing the purpose of the survey, cse study of symptomtic CI (Appendix 1), nd one-pge questionnire (Appendix 2) requesting the doctors to indicte which tretment(s) they prescribed nd which tretments they believed to be most effective for symptomtic CI ptients. options included bse-in prism for reding, reding glsses (no prism), PPT, HBVT, OBVT, nd no tretment (Appendix 2). To determine the clinicl prevlence of CI, we lso surveyed doctors with regrd to the number of symptomtic CI ptients they exmined ech month. The surveys for the optometrists nd ophthlmologists were identicl, except tht we substituted the term orthoptic therpy for vision therpy in the ophthlmology survey. There were three milings to prticipnts: n initil survey, second survey 1 month fter the first survey, nd finlly postcrd reminder. Epi-Info 6.04 D (Center for Disese Control nd Prevention, Atlnt, GA) ws used for double dt entry of both the optometric nd ophthlmologic surveys. All dt processing ws performed using SAS 8.02 (SAS Institute, Inc., Cry, North Crolin) softwre. Men number of ptients (nd CI ptients) ws compred between the two groups using 2-smple t-test. Kruskl-Wllis test ws used to determine if the number of ptients or number of CI ptients seen per week influenced the clinicin s response concerning the use or effectiveness of ech tretment option. Chi-squre tests were used to compre the use nd effectiveness responses given by optometrists nd ophthlmologists. Follow-up comprisons controlling for the number of CI ptients seen per week were performed using logistic regression nlysis. RESULTS Tble 1 summrizes the results of the survey. Fifty-eight percent of the optometrists responded to the survey. The most common tretment ws PPT; 36% often or lwys recommended PPT, 22% often or lwys recommended HBVT incorporting more ctivities thn pencil push-ups, 16% often or lwys prescribed OBVT, 15% often or lwys prescribed bse-in prism glsses, nd 13% often or lwys prescribed reding glsses. Only 3% of the respondents reported tht they generlly did not recommend ny tretment for symptomtic CI ptients. Even though only 16% of the respondents reported tht they prescribed OBVT, 69% felt tht this tretment ws s effective or more effective thn the other tretment modlities in the survey.
TABLE 1. Compring the use nd effectiveness rting for ech tretment option between ophthlmologists (MD) nd optometrists (OD). Percent of ech group responding in ech response option is given. Response Options Group Firly Never Occsionlly Often Often Alwys Use of bse-in prism for reding MD 33.2 48.9 8.4 6.7 2.8 OD 21.3 48.0 16.0 12.9 1.8 Use of reding glsses (no prism) MD 55.9 31.2 8.8 4.1 0.0 OD 42.5 31.5 13.6 10.8 1.7 Use of pencil push-ups MD 11.8 18.8 19.9 22.6 26.9 OD 14.8 29.0 20.5 20.5 15.2 Use of HBVT MD 58.6 17.2 3.5 14.4 6.3 OD 30.7 33.7 13.4 14.5 7.8 Use of OBVT MD 74.1 13.9 6.6 5.4 0.0 OD 60.9 18.3 4.7 10.7 5.4 Use of no tretment, monitor only MD 43.8 39.2 9.2 7.2 0.7 OD 59.3 32.6 4.7 2.8 0.5 ness of bse-in prism for reding MD 11.2 32.3 28.6 21.7 6.2 OD 6.2 35.7 29.6 25.3 3.2 ness of reding glsses (no prism) MD 37.4 39.4 16.8 6.5 0.0 OD 31.5 35.9 17.5 13.6 1.5 ness of pencil push-ups MD 6.3 42.6 29.0 21.6 0.6 OD 8.7 38.6 28.5 21.5 2.7 ness of HBVT MD 19.7 36.9 16.4 25.4 1.6 OD 6.3 26.5 29.6 32.1 5.5 ness of OBVT MD 21.9 31.3 20.8 24.0 2.1 OD 8.6 15.8 17.1 41.2 17.4 ness of no tretment, monitor only MD 40.9 46.5 7.9 4.7 0.0 OD 59.1 33.0 4.8 3.1 0.0 HBVT, home-bsed vision therpy; OBVT, office-bse vision therpy. Modlities for Convergence Insufficiency Scheimn et l. 153 Twenty-three percent of the ophthlmologists (196 totl) responded to the survey. Fifty percent of the ophthlmologists often or lwys recommended PPT, 21% often or lwys recommended HBVT incorporting more ctivities thn pencil push-ups, 5% often or lwys prescribed OBVT, 10% often or lwys prescribed bse-in prism glsses, nd 4% often or lwys prescribed reding glsses. Eight percent of the respondents reported tht they did not recommend tretment for symptomtic CI ptients. In contrst to optometrists, only 4% of ophthlmologists felt OBVT to be more effective thn the other tretment modlities. No sttisticlly significnt difference ws found in the number of ptients exmined per week by the ophthlmologists vs. the optometrists who responded to the survey (30.2 ptients for ophthlmologists nd 27.6 ptients for optometrists, p 0.183). However, there ws significnt difference in the number of symptomtic CI ptients seen per week (0.8 ptients for ophthlmologists nd 1.8 ptients for optometrists, p 0.001). Finlly, from our dt we determined n estimte of the prevlence of CI in both optometric nd ophthlmologicl prctices s 7.5% nd 4%, respectively. Additionl nlyses were performed to compre the use nd effectiveness responses given by optometrists nd ophthlmologists. In ll comprisons, tretment ws considered effective if TABLE 2. Compring the use nd effectiveness rting for ech tretment option between ophthlmologists (MD) nd optometrists (OD). Percent of ech group responding firly often, often, or lwys is reported long with the p vlue from the 2 test compring these percentges between the two groups. Option Use ness MD OD p vlue MD OD p vlue Bse-in prism 18.0 30.7 0.001 56.5 58.0 0.738 for reding Reding glsses 12.9 26.1 0.001 23.2 32.6 0.028 (no prism) Pencil push-ups 69.4 56.3 0.002 51.1 52.7 0.716 HBVT 24.1 35.6 0.006 43.4 67.2 0.001 OBVT 12.0 20.8 0.013 46.9 75.7 0.001 No tretment, monitor 17.0 8.0 0.002 12.6 7.9 0.106 HBVT, home-bsed vision therpy; OBVT, office-bse vision therpy.
154 Modlities for Convergence Insufficiency Scheimn et l. rted firly often, often, or lwys effective, nd regulr use of ny tretment ws defined s firly often, often, or lwys using tht tretment. As shown in Tble 2, the two sets of prctitioners disgreed on the regulr use of ll five tretment options nd the effectiveness of three of the tretment options. Over 50% of respondents in both groups believed bse-in prisms to be effective; however, only 18% of ophthlmologists nd 31% of optometrists regulrly prescribed this tretment. Reding glsses (no prism) were considered effective by 23% of ophthlmologists nd 33% of optometrists, but used regulrly by only 13% of ophthlmologists nd 26% of optometrists. PPT ws the only one of the five tretment options for which the percent of prctitioners who regulrly use the procedure ws greter thn the percent of prctitioners who believed the tretment to be effective. In both groups, bout hlf of the respondents believed pencil push-ups were effective; however, ophthlmologists were more likely to use this tretment option regulrly (69% for ophthlmologists vs. 56% for optometrists). The two groups did not gree on the use or effectiveness of HBVT nd OBVT. Two-thirds of the optometrists reported tht HBVT ws n effective tretment for CI nd 36% regulrly used this tretment. On the other hnd, 43% of ophthlmologists believed HBVT to be effective nd only pproximtely 25% reported regulr use. Optometrists were lso more positive bout the effectiveness of OBVT (76% vs. 47%); however, neither group ws very likely to prescribe it regulrly for CI ptients. In fct, only 21% of optometrists nd 12% of ophthlmologists reported regulr use of OBVT. The overll number of ptients seen per week hd little impct on the use or effectiveness rting given by the clinicin (Tble 3). The responses to the use nd effectiveness of no tretment nd the effectiveness of reding glsses were significntly relted to the number of ptients seen per week (p 0.0118, 0.0018, nd 0.0090, respectively). On the other hnd, the number of CI ptients identified per week influenced the clinicin s responses concerning the use nd effectiveness of four of the six tretment options (Tble 3). The use nd effectiveness of reding glsses, HBVT, OBVT, nd no tretment were ll significntly relted to TABLE 3. p Vlues from test of reltionship between number of ptients nd convergence insufficiency (CI) ptients seen per week nd response to use nd effectiveness of ech tretment option. Option No. of Use No. of CI No. of ness No. of CI Bse-in prism 0.0705 0.5921 0.0968 0.4283 for reding Reding glsses 0.2758 0.0001 0.0090 0.0002 (no prism) Pencil push-ups 0.3394 0.8991 0.1618 0.0454 HBVT 0.3939 0.0001 0.6947 0.0003 OBVT 0.5400 0.0001 0.9129 0.0001 No tretment, monitor 0.0118 0.0002 0.0018 0.0001 HBVT, home-bsed vision therpy; OBVT, office-bse vision therpy. TABLE 4. Adjusted odds rtios (OR) nd p vlues compring the use nd effectiveness rting of ech tretment option between ophthlmologists nd optometrists fter controlling for the number of convergence insufficiency (CI) ptients seen per week. Option the number of CI ptients identified per week. The more CI ptients identified, the more likely the clinicin ws to use OBVT, HBVT, nd reding glsses, nd the less likely the clinicin ws to recommend no tretment. Neither the number of ptients nor the number of CI ptients influenced the clinicins views on the use or effectiveness of bse-in prism for reding or pencil push-ups. Logistic regression nlyses controlling for the number of CI ptients seen per week were performed to compre the reported use nd effectiveness of ech tretment between the two groups. As bove, tretment ws considered effective if rted firly often, often, or lwys effective, nd regulr use ws defined s firly often, often, or lwys using the tretment. The results of these comprisons re displyed in Tble 4. These results indicte tht the ophthlmologists re 55% less likely to use bse-in prism regulrly for reding, 40% less likely to use reding glsses regulrly, but 74% more likely to prescribe PPT regulrly, nd 80% more likely to prescribe no tretment nd simply to monitor the CI. In regrd to reported effectiveness of the vrious tretment options, the logistic regression nlysis shows tht optometrists re 2.6 times (1 vs. 0.38) more likely thn ophthlmologists to report tht HBVT is firly often, often, or lwys effective, nd 3.4 times (1 vs. 0.29) more likely thn ophthlmologists to report tht OBVT is firly often, often, or lwys effective. However, the observed difference in the effectiveness of reding glsses ws no longer significnt (p 0.200). As in Tble 2, the reported effectiveness of ech of the other tretment options did not differ between the groups. DISCUSSION Use ness OR p Vlue OR p Vlue Bse-in prism for reding 0.45 0.001 0.90 0.577 Reding glsses (no prism) 0.56 0.026 0.75 0.200 Pencil push-ups 1.74 0.004 0.89 0.540 HBVT 0.68 0.066 0.38 0.001 OBVT 0.60 0.061 0.29 0.001 No tretment, monitor 1.80 0.045 1.28 0.465 HBVT, home-bsed vision therpy; OBVT, office-bse vision therpy. Although the response rte for the optometrists ws 58%, only 23% of the ophthlmologists responded to our survey. Therefore, we my not hve fully ccurte mesure of how ophthlmologists tret CI. This survey does demonstrte tht most eyecre prctitioners prescribe PPT s the initil tretment for CI. There is little difference in the distribution of other therpeutic regimens such s HBVT, OBVT, or prism prescription. Although there is minimum of scientific support for PPT, it is esy to understnd the clinicl populrity of this tretment, which is both simple nd cost-effective. PPT cn be tught to the ptient, cn be prescribed
in only few minutes, is significntly less expensive for the ptient, nd does not require ny equipment. Most of the optometrists surveyed believed tht OBVT ws the most effective tretment even though they did not prescribe it, indicting difference between wht they do nd wht they believe. OBVT is expensive nd time consuming for the ptient, nd requires n equipped room nd trined personnel (i.e., orthoptist or vision therpy technicin). Thus, unless clinicin is committed to providing this type of therpy, it is not usully prescribed. It is lso possible tht the optometrists did not consider the benefit of OBVT s n offset to the finncil nd time commitment imposed on the ptient. We lso nlyzed the dt to determine if there ws n ssocition between the number of ptients with symptomtic CI seen nd the tretment pproch selected. We found some significnt ssocitions. Clinicins who treted more CI ptients were more likely to report frequent use of reding glsses, HBVT, nd OBVT, while clinicins with the lrgest men number of ptients nd smllest men number of CI ptients (i.e., busy prctices with few CI ptients) were more likely to report use of no tretment nd monitoring only. On the other hnd, clinicins who reported never using the no tretment option, nd perceived monitor only s tretment option, hd the lrgest men number of CI ptients. Finlly, we nlyzed the dt fter controlling for the differences in the number of CI ptients identified ech week. These dt indicted tht ophthlmologists re 1.7 times more likely thn optometrists to prescribe PPT nd 1.8 times more likely thn optometrists to prescribe no tretment nd simply monitor the CI. Compred with optometrists, ophthlmologists re lso less likely to recommend either HBVT or OBVT. In ddition, optometrists re 3.4 times more likely thn ophthlmologists to report OBVT nd 2.6 times more likely thn ophthlmologists to report HBVT s n effective tretment for CI. These dt cn be interpreted simply to men tht clinicins who exmine more CI ptients re more likely to hve developed expertise in prescribing nd implementing both HBVT nd OBVT, nd more likely to consider the use of reding glsses. Another possible interprettion, however, is tht clinicins with n interest in binoculr vision nd vision therpy re more likely to correctly identify ptients with CI, wheres clinicins with less interest my perform n incomplete cse history nd minimum dtbse leding to under detection of CIs in their prctices. Becuse of the lck of interest nd experience with the tretment of CI, these clinicins re less likely to hve the equipment, office spce, nd personnel necessry to implement OBVT or HBVT for CI ptients nd less likely, therefore, to recommend these tretment pproches. Prescribing PPT is ppeling. 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Modlities for Convergence Insufficiency Scheimn et l. 157 APPENDIX 1. Cse study of symptomtic convergence insufficiency (CI) used in survey Convergence Insufficiency Tril (CITT) Survey Cse Study An 18-yer-old mle presents with complints of eyestrin, blurred vision, nd intermittent diplopi ssocited with reding. These symptoms hve been present for the pst 12 months nd occur fter bout 10 to 15 min of reding. There re no medicl problems, he is not tking ny mediction, nd you hve ruled out ny neurologicl/medicl etiology for these symptoms. Assume tht the ptient is highly motivted to find solution to his problem nd is willing to comply with ny tretment pproch you suggest. You find the following: Test Visul cuity t both distnce nd ner Subjective nd cycloplegic refrction Ner point of convergence Cover test t distnce Cover test t ner Fusionl vergence, vergence t ner Accommodtion Results 20/20, OD nd OS OD plno, OS: plno Diplopi t 10 inches from spectcle plne, regins fusion t 14 inches from spectcle plne Orthophori 10 12 exophori Diplopi with 10 bse-out, recovers fusion with 4 bse-out Age-pproprite ccommodtive mplitude nd norml ccommodtive fcility APPENDIX 2. One-pge questionnire 1. Indicte how often you ordinrily recommend the following tretment, for symptomtic CI ptients between the ges of 10 to 35 yers with findings similr to the bove cse? Never Occsionlly Firly Often Often Alwys Bse-in prism for reding Reding glsses (no prism) Pencil push-ups* Home-bsed vision therpy** Office-bsed vision therpy*** No tretment, monitor 2. For the ge group 10 to 35 yers, with findings similr to the bove cse, how effective do you consider the following tretment methods to be for symptomtic CI? Never Occsionlly Firly Often Often Alwys Bse-in prism for reding Reding glsses (no prism) Pencil push-ups* Home-bsed vision therpy** Office-bsed vision therpy*** No tretment, monitor 3. How mny ptients between 10 to 35 yers of ge do you exmine ech week? 4. How mny ptients between 10 to 35 yers of ge do you see ech week tht hve symptomtic CI? *Pencil Push-Ups: **Home-Bsed Therpy: ***Office-Bsed Therpy: Description of Methods Select this ctegory if you tech the ptient how to perform pencil push-ups t home with limited follow-up cre in the office. only t home, e.g., prism, stereoscopes, or ny other devices Select this ctegory if you stisfy both of the following criteri: (1) You schedule ptients for regulr office visits during which n optometrist or therpist performs therpy. (2) Your office vision therpy equipment includes most of the following: Vectogrms, Trnglyphs, stereoscopes, lenses, prisms, computer-ssisted therpy procedures, chistopic, nd orthopic procedures.