macula - on rhegmatogenous retinal detachment ( rd ) is a common cause of ophthalmic emergency that requires surgical treatment in a short period of time to prevent visual loss .
the annual incidence of rd varies according to the recent references between 15.4   and 18.2 per 100  000 , with a peak incidence of 52.5 per 100  000 people between 55 and 59 years of age .
myopia is a major risk factor , with a 4-fold higher risk of rd , compared with a nonmyopic eye , in eyes with mild myopia and a 10-fold higher risk in eyes with moderate and high myopia ( greater than 3 diopters ) .
the risk of rd is 4 times higher in patients who have undergone cataract surgery [ 5 , 6 ] .
the repair of rd has improved during the last 20 years , and today the goal is not only to reattach the retina but to achieve an adequate final vision .
the development of better surgical techniques , such as scleral buckling , pneumatic retinopexy , and pars plana vitrectomy ( ppv ) , has continued to improve the anatomical success rates , going up from 70% to 90% and achieving better functional outcomes [ 79 ] .
nevertheless , proper end vision recovery is a challenge in many cases of rd . besides adequate anatomical reattachment
, other clinical factors have been identified as determinants that prevent a good functional recovery .
the status of the macula is the main factor for a successful functional result [ 1012 ] . even in a successful rd surgery with a clinically normal macular area ,
poor visual acuity ( va ) , color vision defects , and metamorphopsia have been described in successful postoperative rd macula - on surgeries , suggesting the existence of microstructural retina damage .
many series of cases have been reported with excellent anatomical results but not so for the functional outcome after rd surgery .
in fact , many surgeons assume that having macula - on rd will always have a better visual function prognosis than those with macula - off . and there are few papers dealing with this topic .
we performed a pubmed search for english language manuscripts reporting rd and macula - on functional outcomes published since 2003 , and only 4 reports were identified [ 10 , 11 , 13 , 14 ] .
for this reason we have evaluated data collected in a prospective multicentric study including 17 centers in spain and portugal , with data from rds consecutively treated which was primarily designed to add more information on pvr development and clinical risk factors [ 1519 ] .
the purpose of this report is to analyze those macula - on rd cases that were anatomical successful treated but experienced loss of vision at the third month of follow - up .
seventeen clinical ophthalmological institutions in spain and portugal participated in the study [ 1216 ] .
as mentioned the project was designed to improve the sensitivity and specificity of a formula published by rodrguez de la ra et al .   by using clinical factors for calculating the risk of developing proliferative vitreoretinopathy ( pvr ) after rd surgery .
for that project , a database record was created collecting 83 variables that included all pre- , intra- , and postoperative characteristics .
the study protocol was approved by the research committee of the coordinating institution ( ioba , university of valladolid , spain ) and by each of the participating centers .
informed consent was obtained from each patient before inclusion of his / her data in a common database .
all patients consecutively admitted for surgery between october 2004 and february 2008 with rd and a minimum follow - up of three months were considered for inclusion .
for this present analysis only patients with a macula - on rd at the time of the surgery and the macula - on during the entire follow - up were included .
cases of preoperative pvr grade c-1 or higher according to the retina society classification   and posttraumatic rd were excluded .
patients with incomplete data regarding the status of the macula were also excluded from the final analysis . during the period of time when
these patients were included , not all the centers had optical coherent tomography ( oct ) technology available , and it was not considered as a routine component of the rd patient examination . therefore , the status of the macula was determined by indirect ophthalmoscopy and posterior biomicroscopy in the immediate preoperative period ( less than 24 hours before surgery ) . from
the rd patients included in the whole study , 357 had macula - on rds , and they were considered the subject sample of this study .
the patients were divided into 4 groups for further analysis according to the status of the lens and the functional outcome after 3 months of follow - up .
a reduction of at least one line of best corrected va ( bcva ) in the snellen chart at the third month of follow - up was considered as visual loss .
group 1 ( g1 , n = 357 ) included the whole sample of macula - on patients .
group 2 ( g2 , n = 53 ) included macula - on patients with reattached retina and who experienced visual loss at the third month of follow - up .
group 3 ( g3 , n = 39 ) included phakic eyes out of g2 , and group 4 ( g4 , n = 14 ) involved the pseudophakic eyes out of g2 .
the main preoperative characteristics recorded for g2 , g3 , and g4 were retinal breaks type ( tear , hole , dialysis , and giant tear ) , size of retinal breaks in clock hours , extension of rd in quadrants , presence of preoperative pvr less than grade c , previous aphakia , previous vitreous hemorrhage , posterior vitreous detachment , myopia , and preoperative visual acuity ( table 1 ) . only 27 out of the total 83 characteristics gathered in the whole study   were used for the analysis of this report .
surgeons participating in the study were highly experienced in rd treatment and were allowed to treat their patients on their own criteria and according to their personal experience .
the endotamponade with ppv was diverse , including none , air , sf6 , c3f8 , and silicone oil .
most of the technical details of the whole series have been already published [ 1520 ] .
anatomical success was defined as a reattached retina at the last postoperative follow - up at three months .
functional outcome was recorded as bcva with the snellen chart at the initial ( preoperative ) visit and at the final 3-month follow - up visit .
for statistical analysis , bcva data were grouped into three ranges : > 20/40 , 20/50 to 20/100 , and < 20/100 .
qualitative variables were described by percentages and quantitative ones by mean  standard deviation ( sd ) . in all cases , 95% confidence intervals ( 95%ci ) were calculated .
contingency tables were constructed to evaluate the association between categorical rd characteristics and anatomical and functional outcomes .
the independence was checked by chi - square test or fisher 's exact test on sparse tables .
statistical analysis was conducted with spss ( v.19 , spss , chicago , il , usa ) and r software .
the average age of the g1 rd subjects was 52.9  15.6 years when the surgery was performed .
the mean time between onset of rd signs or symptoms and surgery was 13.3  24.9 days , although all patients were macula - on at the time of surgery . comparing the preoperative characteristics of the overall study patients , the g1 patients , all of whom were in the macula - on group , were statistically different for the following ( table 2 ) .
( 1 ) absence of clinical signs of pvr at the preoperative examination was more frequent in g1 .
( 2 ) rd with an extension of 1 quadrant was more frequent in g1 . ( 3 ) percentage of previous cataract surgery in g1 is slightly higher . ( 4 ) eyes without myopia were less frequent in g1 . and
differences for the other pre- , intra- , and postoperative clinical characteristics were not statistically significant . the main preoperative characteristics in g1 compared to the whole study series cohort are shown in table 2 . in g1 ,
345 eyes ( 96.6% ; 95%ci : 9498.2% ) had reattached retinas at the end of follow - up . in 12 eyes ,
the central retina was not reattached ; therefore , they were excluded from further analysis .
single reattachment procedures included ppv ( 67.2% ; 95%ci : 62.172% ) , scleral buckle ( 57.7% , 95%ci : 52.4% ; 62.9% ) , and explant ( 11.9% ; 95%ci : 8.815.9% ) .
the mean bcva in g1 was 0.57  0.3 in the preoperative visit and 0.59  0.29 at 3 months of follow - up .
the preoperative va in g1 was < 20/100 in 44 patients ( 12.3% ; 95%ci : 8.9% , 15.7% ) , between 20/100 and 20/40 in 79 eyes ( 22.1% ; 95%ci : 17.8% , 26.4% ) , and > 20/40 in 234 eyes ( 65.6% ; 95%ci : 60.6% , 70.5% ) ( table 2 ) .
the postoperative va in this group at the end of the follow - up was < 20/100 in 37 eyes ( 10.4% ; 95%ci : 7.2% , 13.5% ) , between 20/100 and 20/40 in 80 eyes ( 22.4% ; 95%ci : 18.1% , 26.7% ) , and > 20/40 in 240 eyes ( 67.2% ; 95%ci : 62.4% , 72.1% ) .
twenty - six out of 37 eyes with a final va < 20/100 ( 7.3% ; 95%ci : 4.9% , 10.6% ) had a decreased va at the end of the follow - up .
in g2 ( table 1 ) , which included phakic and pseudophakic eyes with reattached retinas and visual loss , the final va , 0.23  0.14 , was lower than the initial va , 0.65  0.25 ( p < 0.0001 , paired t - test ) , despite reattachment of the retina .
ppv was the most commonly performed surgery ( 88.7% ; 95%ci : 80.297.2% ) followed by scleral buckle surgery ( 58.5% ; 95%ci : 45.271.8% ) . in some cases , both procedures were used . in g3 ( tables 1 and 3 ) , which included 39 phakic eyes with reattached retinas but with a reduction in va at the end of follow - up ,
the mean time between onset of rd and surgery was 17.7  24.9 days . in the preoperative va evaluation
, 82.1% of eyes ( n = 32 ) had > 20/40 and none of them had < 20/100 but at the end of the third month 30.8% ( n = 12 ) had < 20/100 .
the main preoperative characteristics of this group were the following : ( 1 ) no pvr was present in 48.7% , whereas pvr grades a and b were present in 33.3% and 17.9% , respectively , ( 2 ) a visible retinal tear and a unique break were present in 97.4% and 52.6% , respectively , ( 3 ) rd extensions of 2 to 3 quadrants were found in 59% and complete posterior vitreous detachment ( pvd ) was present in 53,8% of eyes , and ( 4 ) ppv was performed on 87.2% ( 95%ci : 71.895.2% ) of the patients and scleral buckle surgery on 64.1% ( 95%ci : 47.278.3% ) .
some patients received both procedures . in g4 ( tables 1 and 4 ) , which comprised 14 pseudophakic patients with macula - on and successful surgery but who had visual loss at the end of the follow - up , the average age was 63.3  14.4 years .
the initial va was > 20/40 in 12 eyes ( 85.7% ) . at the end of the follow - up , the va was < 20/100 in 50% and between 20/100 and 20/40 in 50% of the cases ( table 4 ) .
ppv was performed on 92.9% ( 95%ci : 85.9% ; 99.8% ) of the patients and scleral buckle surgery on 42.9% ( 95%ci : 29.5 ; 56.2% ) ( p < 0.05 ) .
while there are published data regarding the improvement of anatomical results of rd surgery , there are few reports showing whether or not rd surgery results in functional improvement [ 911 , 13 , 14 , 23 , 24 ] and , to the best of our knowledge , there is only a report regarding visual loss in macula - on rd after successful surgery . for rd certain variables
are thought to be significant predictors for functional outcome , for instance , the status of the macula ( which is the most important factor ) , macular elevation when detached , and other factors such as age of the patient [ 9 , 25 ] , poor initial vision [ 9 , 25 ] , and interval between onset of rd and surgery [ 23 , 2729 ]
. it is generally assumed by most surgeons that the  macula - on  status before surgery guarantees good functional results , which in most cases means to preserve the patients previous va .
however , we have experienced macula - on rd cases in which despite successful surgery the visual results were not favorable .
this experience is common among the retinal surgeons but as mentioned there is no specific publication on this topic .
thus , although the original study was not specifically set up to investigate this event , we used its data to analyze the frequency of unfavorable outcomes and to add some clinical information . in this study , 53 out of 357 patients ( 14.9% ; 95%ci : 11.419.1% ) meeting the inclusion criteria experienced a worsening of va after rd surgery although the macula was attached .
the american academy of ophthalmology has recognized that the status of the macula is the major factor related to visual prognosis .
it recommends that when the rd does not affect the macula , repair should be made within the first 24 hours following the diagnosis . in our series , the mean time between the onset of the symptoms and surgery was 13.3    24.9 days .
nevertheless , the surgery was always performed within 72 hours after the admittance at the hospital , although symptoms started several days before . because the central vision was not affected by the rd ,
it is likely that both the patients and the general practitioners underestimated the severity of the disease and that may explain the delayed diagnosis .
in addition , photopsias could appear several days or even weeks before the development of rd .
this long interval before surgery was already mentioned by our group and could be a fact related to the structure of the national health system , where most of the patients complaining floaters or flashes are referred to the general practitioner instead of ophthalmologist ( gp ) [ 16 , 30 ] .
it is acknowledged that the time interval to surgery is crucial to prevent progression of subretinal fluid into the macula and disruption of the photoreceptors , causing a possible loss of va in some cases . for our patients with macula - on rds ,
the evaluations were made only by indirect ophthalmoscopy or fundus biomicroscopy at 24 or 48 hours prior to the surgery .
thus , it is possible that we could not detect the presence of a small amount of subretinal fluid under the macula as a limitation of this study .
it is possible that systematic analysis of the status of the macula by oct may increase the number of macula - off patients and also that structural changes in patients with visual loss could be detected .
recent studies used fourier - domain oct to evaluate postoperatively both macula - on and macula - off rds [ 32 , 33 ] .
foveal anatomical abnormalities were discovered in 62% of the patients . in macula - off cases , there was disruption of the photoreceptor inner segment / outer segment ( is / os ) junction line ( which correspond to the ellipsoid portion of the photoreceptors : ellipsoid ) in 61% of the cases , and the external limiting membrane ( elm ) was observed only in 24% .
when followed up overtime , the restoration of a normal is / os line occurred only in eyes without an initially disrupted elm as the investigators also noted .
eyes in which the is / os junction returned to normal showed better va than those in which this change did not take place .
it is important to take into consideration , however , that although oct is currently a widespread tool , it could take time until patient performs it .
considering the timing for the management of this kind of rd , oct become sometimes indispensable auxiliary test .
as mentioned we did not perform oct on patients preoperatively to rule out a subclinical extension of subretinal fluid under the fovea , a reason which could explain why some eyes with similar alterations have functional results significantly better than others .
for phakic eyes that experienced loss of vision in spite of successful surgery , especially in those operated by vitrectomy , it is possible that the low vision could have been caused by the progression of cataracts . however , there were 14 pseudophakic eyes in the g4 group that experienced visual loss that could not be attributed to progression of lens opacity .
some factors such as intraoperative complications like rise intraocular pressure ( iop ) and microscope light toxicity during the surgery , as well as the use of silicon oil or gas as tamponade , could have produced retinal damage , causing a reduction in the inner retinal thickness due to neuronal cell loss in the macular area .
however , no postsurgical rise in iop was detected in this series and no one received silicon oil tamponade in these groups , so these variables can be safely excluded as the cause of visual loss in our patients .
neither epiretinal membranes nor cystoid macular edema , which are also causes of visual loss after rd surgery , was identified in the follow - up .
when these conditions were suspected most of the patients were evaluated by oct , when possible .
as no clinical differences were found between groups , further investigations should elucidate if causes of visual loss are related to a gross anatomic factor or could be a photoreceptor damage caused by diffusible factors released by ischemic detached retina .
in fact oxidative damage and tnf- are factors used experimentally for inducing damage to the rpe cells and photoreceptors .
finally , analysis of retinas after experimental retinal detachments in cats reveals that ultrastructural changes ( apoptosis , gliosis ) occur beyond the specific area of the detached retina .
these changes could be one the reasons of the impairment of vision in our patients .
first is that the study design was not intended to solve the question of vision loss in patients with macula - on rd , but , in view of the lack of reports on va loss after macula - on rd surgery , we have considered that our data could be interesting .
second limitation is that at the time of inclusion of patients oct was not available in all centers , and those having this technology had no similar equipment .
so there is no way to know for sure if the data may be extrapolated to other geographical areas , although our retina 1 project reports have yielded similar results of rd surgery to those obtained by other neighboring countries [ 9 , 12 , 35 , 40 ] .
in summary , we have added information on the prevalence of the clinically significant loss of va following rd with macula - on surgery , a condition affecting a relevant percentage of patients . neither clinical nor surgical factors were identified as responsible .
this topic deserves further study , incorporating new technical devices such as swept source oct that is able to identify structural changes at the level of the inner retina .
biochemical studies could also elucidate in the future whether or not any molecule released by the detached retina may be responsible for this damage .
 
 purpose . to quantify the frequency of visual loss after successful retinal detachment ( rd ) surgery in macula - on patients in a multicentric , prospective series of rd 
 . methods . clinical variables from consecutive macula - on rd patients were collected in a prospective multicentric study . 
 visual loss was defined as at least a reduction in one line in best corrected visual acuity ( va ) with snellen chart . 
 the series were divided into 4 subgroups : ( 1 ) all macula - on eyes ( n = 357 ) ; ( 2 ) macula - on patients with visual loss at the third month of follow - up ( n = 53 ) which were further subdivided in ( 3 ) phakic eyes ( n = 39 ) ; and ( 4 ) pseudophakic eyes ( n = 14 ) . 
 results . 
 fifty - three eyes ( 14.9% ) had visual loss three months after surgery ( n = 39 phakic eyes ; n = 14 pseudophakic eyes ) . there were no statistically significant differences between them regarding their clinical characteristics . 
 pars plana vitrectomy ( ppv ) was used in 67.2% of cases , scleral buckle in 57.7% , and scleral explant in 11.9% ( 36.1% were combined procedures ) . 
 conclusions . around 15% of macula - on rd eyes lose va after successful surgery . 
 development of cataracts may be one cause in phakic eyes , but vision loss in pseudophakic eyes could have other explanations such as the effect of released factors produced by retinal ischemia on the macula area . 
 further investigations are necessary to elucidate this hypothesis . 
1. Introduction
2. Methods
3. Results
4. Discussion
5. Conclusions