(2002) 16, 771 777 2002 Nture Publishing Group All rights reserved 0950-222X/02 $25.00 www.nture.com/eye JA Thompson 1, MP Sned 2, BM Billington 3, Ntionl udit of the T Brrie 4, JR Thompson 5 nd JM Sprrow 6 outcome of primry surgery for rhegmtogenous retinl detchment. II. Clinicl outcomes CLINICAL STUDY Abstrct Purpose This ntionl study ws designed to udit ntomicl outcome nd complictions relting to primry surgery for rhegmtogenous retinl detchments. This pper presents success nd compliction rtes, nd exmines vritions in outcome. Methods Smpling nd recruitment detils of this ntionwide cross-sectionl survey of 768 ptients of 167 consultnt ophthlmologists hving their first opertion for rhegmtogenous retinl detchment hve been described. The min clinicl outcomes detiled here re ntomicl rettchment t 3 months fter surgery nd complictions relted to surgery. Consultnts with declred specil interest in retinl surgery nd ble to perform prs pln vitrectomy were designted specilists for the nlyses. Results Overll rettchment rte with single procedure ws 77% (95% CI 73.9 80.2). There were significnt differences in rettchment rtes between specilists nd non-specilists. Without llowing for csemix, specilists hd rettchment rte of 82% (95% CI 77.9 85.7) with single procedure nd non-specilists 71% (95% CI 65.9 76.0). Allowing for cse-mix, there ws significnt difference between specilists nd non-specilists for grde 2 detchments of 87% nd 70% respectively (P 0.0001). Anlysing detchments by brek type, the lrgest difference between specilists nd non-specilists ws observed for retinl detchments secondry to horseshoe ters, 80% nd 68% respectively (P 0.003). Specilists met the stndrds set for primry rettchment rtes, while non-specilists did not. Over third of ptients hd t lest one compliction reported t some point during the udit period. Conclusions Significnt differences were seen in rettchment rtes between specilists nd non-specilists, overll nd for specific subgroups of ptients. This study provides relevnt, robust nd vlid stndrds to enble ll surgeons to udit their own surgicl outcomes for primry retinl detchment repir in rhegmtogenous retinl detchments, identify common ctegories of filure nd im to improve results. (2002) 16, 771 777. doi:10.1038/ sj.eye.6700325 Keywords: retinl detchment repir; Ntionl Survey; outcomes; udit Introduction Prior to Gonin s understnding of the pthophysiology of retinl detchment, surgicl or spontneous cure ws rre. 1,2 He lid the foundtions for successful retinl detchment surgery in the 1920s in lrgely unselected series 3 nd the proportion of ptients judged suitble for surgery nd the proportion of ptients with successful ntomicl outcome rose over the following decdes. 4 6 Vrition exists in the rettchment rtes of published series for resons which remin uncler. 7 11 With such vrition existing in the literture nd no consensus on how to explin the differences, setting robust, vlid nd relevnt stndrds for locl udit becomes difficult. This ntionl study hs focused on primry surgery for rhegmtogenous retinl detchment nd the design llowed the success rtes for detchments of differing morphology to be exmined in detil. 1 Royl College of Ophthlmologists, London, UK 2 Vitreoretinl Service, Addenbrookes Hospitl, Cmbridge, UK 3 Deprtment of Ophthlmology, Royl Berkshire Hospitl, Reding, UK 4 Tennnt Institute of Ophthlmology, Grtnvel Generl Hospitl, Glsgow, UK 5 Deprtment of Ophthlmology, Leicester University, Leicester, UK 6 Bristol Hospitl, Bristol, UK Correspondence: JA Thompson, Royl College of Ophthlmologists, 17 Cornwll Terrce, London NW1 4QW, UK Tel: + 44 (0) 20 7935 0702 Fx: + 44 (0) 20 7935 9838 E-mil: julietthompson@ doctors.net.uk Received: 7 Februry 2002 Accepted in revised form: 11 June 2002
772 Ntionl detchment udit Outcomes JA Thompson et l Methods The methodology nd vlidtion studies hve been described in detil in our previous pper 12 but in summry, clinicl dt were collected in ntionl cross-sectionl survey of ll consultnts who performed retinl detchment surgery in the Ntionl Helth Service. Consultnts selected ptients undergoing primry surgery for simple rhegmtogenous retinl detchments ccording to study eligibility criteri nd supplied dt on ptients pre-opertive fctors, type of surgery, ntomicl outcome nd complictions. The min outcome mesure ws complete retinl rettchment t 3 months post-opertively. Secondry outcome mesures were compliction rtes. These were compred to pre-determined udit stndrds set by the steering committee. 12 Detchments were grded into four ctegories for subgroup nlysis. 12 Results Rettchment Antomicl outcome t 3 months ws known in 95.3% (732/768) of the eligible ptients. Tble 1 outlines the mngement of ll ptients by specilists nd nonspecilists respectively. The rettchment rtes t 3 months re given in Tble 2. Bering in mind reported ctivity rtes, 12 the estimted nnul success rte for primry rhegmtogenous retinl detchments in the United Kingdom (UK) is 81.0% for ll ptients fter single procedure. This equtes to 8339 of the 10 284 primry procedures for rhegmtogenous retinl detchment being successful. Success rtes by specilist interest The rtes of rettchment by specilist interest re shown in Tble 3. Specilists hve significntly higher rettchment rtes t 3 months thn non-specilists for both single procedure to rettchment nd when Tble 2 Number of surgicl procedures Overll rettchment rtes where outcome is known Complete ntomicl rettchment t 3 months n % 95% CI Single procedure only 561/728 77.1 73.9 80.2 Multiple procedures by 622/728 85.4 83.4 88.6 sme surgeon Multiple procedures by 661/728 90.8 88.6 92.9 more thn one surgeon Includes five ptients where it is not known whether or not originl surgeon performed second opertion. Tble 1 Overll mngement of ll ptients included in the study by specilist interest nd retinl outcome Specilists Non-specilist Retin completely re-ttched t 3 months Single procedure 329 232 Multiple procedure by sme surgeon 38 23 Multiple procedures by more thn one surgeon 6 28 Unknown whether second surgeon performed second opertion 1 4 Subtotl 374 287 Retin not ttched t 3 months Further surgery by originl surgeon nd outcome wited 13 4 Referred to nother surgeon for further mngement 1 32 Ptient refused further surgery/referrl 6 3 No further surgery or referrl on clinicl grounds 6 1 Unknown mngement 1 Subtotl 27 40 Retinl outcome not known t 3 months Dischrge before 3 months 6 2 Referred bck to referring clinicin 8 Referred to nother consultnt for locl follow-up 2 6 Lost to follow-up 5 3 Notes incomplete 1 Died 1 Not recorded 1 1 Referred for further mngement 4 Subtotl 24 16 Overll Totl 425 343
Ntionl detchment udit Outcomes JA Thompson et l 773 Tble 3 Rettchment rtes t 3 months by specilist interest where outcome is known Rettched by single procedure Rettched by multiple procedures by sme surgeon n % 95% CI n % 95% CI Specilist 329/401 82.0 77.9 85.7 367/401 91.5 88.6 94.3 Non-specilist 232/327 70.9 65.9 76.0 255/327 78.0 74.3 83.5 P 0.001 P 0.001 P = significnce of difference between specilists nd non-specilists by logistic regression djusting for cluster smpling. multiple procedures by the sme surgeon hve been crried out. These results hve not been djusted for cse-mix. Non-specilists fil to meet the stndrds set for the udit 12 for ntomicl rettchment for both single nd multiple procedures. A number of ptients were lost to follow-up t 3 months but whether their retin hd rettched or not following surgery ws known t 1 month. The rettchment rte for specilists t one month hs incresed slightly compred to 3 months, to 82.5% (340/412), s number of ptients with successful surgery who were dischrged erly hve been included. The rettchment rte for non-specilists t one month hs decresed slightly compred to 3 months, to 70.2% (236/334). Success rtes by grde of surgeon When the proportion of ptients who hd successful ntomicl rettchment with single procedure ws exmined by grde of surgeon, specilist consultnts hd the highest success rtes. For most detchments in the study, the primry surgeon ws consultnt. A non-consultnt ws the primry surgeon for reltively few detchments nd with the exception of fellows their results fll below the stndrds for the udit, 12 whether supervised by consultnt or not. Rettchment rtes for ech grde of surgeon re given in Tble 4. The rettchment rtes when non- Tble 4 Rettchment rtes t 3 months for single procedure by grde of primry surgeon Grde of surgeon Rettched by single procedure n % 95% CI Specilist consultnt 234/281 83 78 87 Non-specilist consultnt 203/278 73 67 78 SpR 80/110 73 63 81 Fellow 35/43 81 67 92 Senior house officer 3/6 50 12 88 Non-consultnt creer grde 5/8 63 24 91 surgeon Specilist Registrr, registrr or senior registrr. consultnts were the primry surgeons re given by grde of ssistnt in Tble 5. Success rtes by grde of detchment Rettchment rtes by grde of procedure nd type of opertive procedure used re given in Tble 6. Grde 1 detchments, single ter with less thn 1 qudrnt of ssocited retinl detchment, hd the best rtes of rettchment, though over 11% of those operted on by specilists, nd 15% of those operted on by nonspecilists filed to be rettched with single procedure. Specilists used conventionl dringe surgery in higher proportion of grde 1 detchments thn non-specilists, though rettchment rtes were similr. Nine ptients hd prs pln vitrectomy for grde 1 detchment. The most significnt difference in rettchment rtes between specilists nd non-specilists ws seen with grde 2 detchments (single or multiple breks within the sme qudrnt nd/or less thn two qudrnts of retinl detchment), 87% nd 70% respectively. This ws lso the lrgest group of detchments in the study. The rettchment rte for specilists differs little from their rte for grde 1, but the filure rte for single procedure ws double for non-specilists, due to prepondernce of erly filures. The rettchment rtes for the more complex grde 3 detchments were lower compred to grdes 1 nd 2, by specilists nd more so by non-specilists. Nonspecilists performed fewer grde 3 detchments thn specilists nd the disprity in ctivity between the two groups of surgeons increses for grde 4. Morphologiclly, grde 4 ws heterogeneous group of detchments nd it would be difficult to comment on the success rtes for either group of surgeons. Success rtes by brek type Tble 7 gives rettchment rtes for detchments strtified ccording to the nture of the retinl brek. The rettchment rtes for horseshoe ters re mrginlly lower thn the overll rtes nd there is significnt difference between specilists nd non-
774 Ntionl detchment udit Outcomes JA Thompson et l Tble 5 Rettchment rtes t 3 months for single procedure where non-consultnt ws primry surgeon by grde of ssistnt Surgeon Assistnt Overll Specilist Non- SpR Fellow SHO Middle Nurse None Not consultnt specilist grde recorded consultnt n % n % n % n % n % n % n % n % n % n % SpR 36/47 77 13/23 57 5/8 63 8/8 100 6/8 75 6/7 86 1/1 100 5/8 63 80/110 73 Fellow 7/9 78 11/12 92 2/2 100 3/3 100 2/3 67 1/1 100 9/13 69 35/43 81 Senior house officer 2/2 100 1/3 33 0/1 0 3/6 50 Non-consultnt creer grde surgeon 1/1 100 2/2 100 1/1 100 0/3 0 1/1 100 5/8 63 Specilist Registrr, registrr or senior registrr. Tble 6 Rettchment rtes following single procedure by grde of detchment nd by type of opertive procedure (cell %) Grde 1 Grde 2 Grde 3 Grde 4 Non-drin Drin b PPV c All methods Non-drin Drin PPV All methods Non-drin Drin PPV All methods Non-drin Drin PPV All methods Overll 86 77 72 70 (127/147) (258/334) (110/152) (63/90) Specilist 87 88 100 89 81 89 90 87 82 74 82 78 44 82 71 71 (26/30) (21/24) (9/9) (56/63) (38/47) (79/89) (27/30) (144/166) (9/11) (40/54) (27/33) (76/98) (4/9) (18/22) (29/41) (51/72) Non-specilist 84 86 85 62 70 68 50 67 63 0 69 100 67 (53/63) (18/21) (71/84) (33/53) (81/115) (114/168) (6/12) (28/42) (34/54) (0/2) (9/13) (3/3) (12/18) d P 0.771 0.909 0.475 0.073 0.004 0.001 0.189 0.474 0.093 0.762 Non-drin = conventionl sclerl buckling without dringe. b Drin = conventionl sclerl buckling with dringe. c PPV = prs pln vitrectomy. d P = significnce of difference between specilists nd non-specilists by logistic regression djusting for cluster smpling.
Ntionl detchment udit Outcomes JA Thompson et l 775 Tble 7 Rettchment rtes following single procedure by brek type Horseshoe ter(s) Retinl hole(s) only Mixed holes nd Dilysis Gint ters No hole seen preonly ters opertively n % n % n % n % n % n % Overll 284/379 75 155/195 79 48/60 80 52/63 83 19/25 76 Specilists 173/215 80 84/97 87 30/36 83 29/34 85 3/5 60 10/14 71 Non- 111/164 68 71/98 72 18/24 75 23/29 79 9/11 82 specilists P 0.003 0.020 0.431 0.554 0.497 P = significnce of difference between specilists nd non-specilists by logistic regression djusting for cluster smpling. specilists. Rettchment rtes for both groups of surgeons re slightly higher for single procedure for retinl holes thn their overll rtes nd while sttisticlly significnt difference remins between the two groups, it is less mrked. The numbers of detchments in the mixed ter nd hole group is smller thn the first two groups. The difference in rettchment rtes between the two groups is not sttisticlly significnt. Though the numbers in the dilysis group re smll, they hve better rettchment rtes thn other types of breks with similr rtes for both groups of surgeons. There were few detchments secondry to gint retinl ters nd specilists performed ll surgery. The rettchment rte is well below the overll rte. Multivrite nlysis The results of multivrite nlysis show tht specilist sttus ws the most importnt indictor of successful ntomicl rettchment with single procedure. Allowing for the other fctors, ptients operted on by specilists were over three times more likely to hve successful ntomicl rettchment with single procedure (odds rtio 3.6, 95% CI 2.2 5.9). Incresing grde ws ssocited with decresed likelihood of successful ntomicl rettchment. Grde 2 detchments were nerly three times less likely to rettch with single procedure compred to grde 1 (odds rtio 0.36, 95% CI 0.16 0.84). Grde 3 nd grde 4 were even less likely to rettch compred to grde 1 hving odds rtio 0.17 (95% CI 0.07 0.41) nd 0.15 (95% CI 0.05 0.40) respectively. The dely between presenttion nd surgery rnged from 0 to 552 dys (medin 2 dys). Ptients with dely between presenttion nd surgery of over 30 dys, were slightly more likely to hve successful ntomicl result compred to ptients whose opertion ws performed within 1 dy of presenttion (odds rtio 4.5 95% CI 1.1 18.6). This supports the notion tht ptients who were selected to wit for surgery were those who hd good prognosis for rettchment nd tht delying their surgery did not chnge this. Type of surgery, brek type nd high-risk sttus were not ssocited with poorer outcome in the multivrite nlysis. Complictions Over one third of ptients hd t lest one compliction noted t some point in the 3-month follow-up period. Overll compliction rtes for ech time point re shown in Tble 8. There ws no significnt difference between the overll complictions rte of specilists nd non-specilists. Per-opertive complictions The rte for reported unplnned sub-retinl fluid dringe ws 2.7% (21/768) nd tht for retinl incrcertion 0.7% (5/768). The smple met the udit stndrds 12 for retinl incrcertion nd unplnned sub-retinl fluid dringe nd there ws no significnt difference between specilists nd non-specilists. Other complictions reported included cornel brsion (five ptients), sclerl rupture (two ptients), elevted intr-oculr pressure requiring intervention (eight ptients), nd itrogenic brek (six ptients). Itrogenic breks occurred only in ptients undergoing prs pln vitrectomy, which gives rte of 4.9% (6/122) for itrogenic brek for ptients hving prs pln vitrectomy in this cohort. Informtion ws specificlly sought on intr-oculr hemorrhge. In totl, 7.2% (55/759) ptients were reported to hve hd n intr- Tble 8 Proportion of ptients with compliction reported by time in follow-up period n % At ny time during follow-up 255/722 35.3 Per-opertive 109/759 14.4 Erly (within 1 month) 68/762 8.9 Lte (1 3 months) 139/707 19.7
776 Ntionl detchment udit Outcomes JA Thompson et l oculr hemorrhge, but detils of the site, extent nd significnce were not generlly reported. Erly complictions Only one ptient developed endophthlmitis postopertively (0.1%). The smple met the udit stndrds 12 for endophthlmitis. Other reported complictions in the erly post-opertive period included diplopi (six ptients), elevted intr-oculr pressure (13 ptients), choroidl effusion (four ptients), ctrct (four ptients), plomb problems (four ptients) nd vitreous hemorrhge (four ptients). Lte complictions The reported rte for mculr pucker ws 4.4% (34/768), prolifertive vitreoretinopthy ws 4.8% (37/768) nd lte diplopi ws 2.6% (20/768). The smple met the udit stndrds 12 for these complictions nd there ws no sttisticlly significnt difference in rtes between specilists nd nonspecilists. A significntly higher proportion of nonspecilists cses hd explnt relted complictions thn specilists cses (14/343, 5/425 respectively, P 0.04) during the 3-month follow-up. Other recorded complictions in the lte post-opertive period were ctrct (12 ptients), cystoid mculr oedem (three ptients), uveitis (three ptients), nterior segment ischemi (one ptient), nd rubeosis (one ptient). Discussion Overll the smple met the udit stndrds 12 for rettchment but this combined outcome mesure concels difference in rettchment rtes between specilists nd non-specilists. Most non-specilists performed few detchments nnully nd their lower success rte my be relted to this or poor cse selection. Other thn for the simplest detchments (grde 1 single retinl brek with less thn one qudrnt of ssocited retinl detchment) nd dilyses, non-specilists perform below the rettchment rtes chieved by specilists. Nonspecilists hve the option of choosing which detchments to operte on nd which to refer, so tht rettchment rtes should be demonstrbly comprble to or better thn those of specilists if surgery by nonspecilists is to be justified nd sustinble in terms of clinicl governnce. The results for grde 1 surgery were bove the set stndrd, 12 lthough mny specilists would be disppointed t filure rte of over 11% for grde 1 detchments. Grde 2 detchments (single or multiple breks within the sme qudrnt nd/or less thn two qudrnts of retinl detchment) formed the lrgest group of detchments within the survey. The sttisticlly significnt differences in rettchment rtes between specilists nd non-specilists persists even in the cohort limited to conventionl surgery implying tht surgicl technique in ddition to cse selection is significnt. Erly filures generlly result from incomplete closure of breks t primry surgery or missed primry breks. 13,14 The fct tht missed breks re significnt implies tht successful mngement of retinl detchment requires good surgicl skills, creful cse selection nd meticulous exmintion of the ptient prior to surgery, in order tht ll retinl breks nd other relevnt retinl pthology be identified nd mnged ppropritely. 15 The low rtes of surgery performed by non-specilists, possibly reflecting in prt low numbers of ptients presenting to them with retinl detchments, my not be sufficient to mintin such clinicl nd surgicl skills thereby contributing to higher filure rtes. Non-consultnts were the primry surgeons in reltively few detchment repirs. With the exception of fellows, their rettchment rtes fell well below the stndrd set for the udit. Specilist registrrs when ssisted by non-specilist consultnt hd fr lower rettchment rtes thn those ssisted by specilist consultnts, which suggests tht the trining offered in such circumstnces, my be indequte. The compliction rtes for trinees were similr to those of consultnts, indicting tht primry filures were not secondry to complictions but poorly performed surgery. Creful ptient selection hs been shown to provide cceptble rettchment results for trinees. 9 In the context of clinicl governnce, trining must be shown not to compromise ptient sfety. The retrospective design of the study could led to under-reporting of complictions. Despite this, over one third of ptients were reported to hve hd t lest one compliction reported during the 3-month followup period. The stndrds set for complictions were met, nd in some circumstnces the reported rtes were better thn the udit requirements. The only compliction with different rtes between specilists nd non-specilists ws protruding explnts. The previous comments bout the mintennce of surgicl skills my similrly pply in this instnce. Until recently ll surgeons in the UK were required to perform retinl detchment surgery before the wrd of certificte of higher surgicl trining. Recent chnges to trining progrmmes hve removed the requirement for trinees to perform ny prcticl retinl surgery. Unless trinee surgeons hve
Ntionl detchment udit Outcomes JA Thompson et l 777 undertken specilist trining in retinl surgery, they cnnot be expected to hve sufficient expertise in the surgicl mngement of retinl detchments on becoming consultnt. To dte there hs been no co-ordinted plnning for the provision of surgicl retinl services in the UK nd the current service hs developed in n d hoc fshion with wide regionl vritions in the numbers of specilist retinl surgeons. Historiclly there hs been drift towrds retinl surgery being performed incresingly by retinl sub-specilists. The results of this udit confirm tht retinl sub-specilists do on verge chieve better surgicl outcomes compred with non-specilists. If primry retinl detchment surgery were to be performed exclusively by subspecilists there would be need to expnd specilist centres in ech region. Such chnge in prctice would hve significnt resource implictions nd would impct not only on provision of ptient cre but lso on surgicl trining. The uthors do not consider it their role to formulte recommendtions regrding service provision bsed on the results of this udit nd this study neither endorses nor refutes the prctice of ny individul surgeon. These results do however support the notion tht surgeons with declred interest, specilist post-grdute trining, nd greter throughput of retinl detchment cses chieve better surgicl outcomes. This ntionl udit provides n indiction of success rtes for vriety of groups of surgeons nd suggests possible res of concern, where performnce my not be s good s expected. It is hoped tht these results, nd the stndrds set by the steering committee, will be useful s benchmrks ginst which ll surgeons cn judge themselves when uditing their own surgicl prctice to improve further on primry success rtes. Outcome informtion in reltion to cse mix my ssist non-specilist surgeons in deciding which ptients to operte on nd which to refer on to retinl specilist. Acknowledgements The uthors would like to thnk ll the consultnts who prticipted in both phses of the udit without whose support the study would not hve been possible. They would lso like to thnk Mr AH Chignell nd Mr B Foot for prticipting in the steering committee; Mr AT Moore s pst chirmn of the udit committee; Miss M Hllendorff nd the stff of the Royl College of Ophthlmologists nd Mr CR Cnning nd Mr A Chopdr for piloting the clinicl questionnires. This study ws supported by core udit funding from the Deprtment of Helth. Presented in prt t the Royl College of Ophthlmologists Annul Congress 1999 nd 2000 nd the Oxford Ophthlmologicl Congress 2000. Finncil/proprietry interest: None. References 1 Gonin J. L tritement locl du décollement rétinien. Revue Generl Ophthlmologie 1929; 43: 381 386. 2 Gonin J. Guérisons opértoires de décollements rétiniens. Revue Generl d Ophthlmologie 1923; 37: 337 340. 3 Gonin J. Le Décollement de l Rétine. Pthogénie Tritment. Librrie Pyot et Cie: Lusnne, 1934. 4 Rosengren B. Results of tretment of detchment of the retin with dithermy nd injection of ir into the vitreous. Act Ophthlmologic 1938; 16: 573 579. 5 Smith TR, Pierce LH. Idiopthic detchment of the retin. Arch Ophthlmol 1953; 49: 36 44. 6 Dufour R, Erpelding G. Resultt du tritement en fonction de l sitution clinique. Mod Probl Ophthl 1965; 3: 229 248. 7 Sullivn PM, Luff AJ, Aylwrd GW. Results of primry rettchment surgery: A prospective udit. 1997; 11: 869 871. 8 Lidlw DAH, Clrk B, Grey RHB, Mrkhm RHC. (letter). 1998; 12: 751. 9 Comer MB, Newmn DK, George ND, Mrtin KR, Tom BDR, Moore AT. Who should mnge primry retinl detchments? 2000; 14: 572 578. 10 Minihn M, Tnner V, Willimson TH. Primry rhegmtogenous retinl detchment: 20 yers of chnge. Br J Ophthlmol 2001; 85: 546 548. 11 Ah-Ft FG, Shrm MC, Mjid MA, McGllird JN, Wong D. Trends in vitreoretinl surgery t tertiry referrl centre: 1987 to 1996. Br J Ophthlmol 1999; 83: 396 398. 12 Thompson JA, Sned MP, Billington BM, Brrie T, Thompson JR, Sprrow JM. Ntionl udit of the outcome of primry surgery for rhegmtogenous retinl detchment. I. Smple nd methods. 2002; 16: 766 770. 13 Chignell AH, Fison LG, Dvies EWG, Hrtley RE, Gundry MF. Filure in retinl detchment surgery. Br J Ophthlmol 1973; 57: 525 530. 14 Wilkinson CP, Brdford RH. Complictions of drining subretinl fluid. Retin 1984; 4: 1 4. 15 Tsmn W. History of retin 1896 1996. Ophthlmology 1996; 103: S143 S152.