Years Of Cataract Surgery Research Articles

Intraocular Lens (IOL) Exchange Procedure in Refractive Surprise After Ten Years of Cataract Surgery

Introduction: Postoperative refractive surprises may manifest following cataract surgery. A residual refraction difference of > 2.0 D after cataract surgery was considered a refractive surprise. Treating refractive error after cataract surgery includes non-surgical and surgical options. The objective is to report clinical outcomes of intraocular lens (IOL) exchange with ciliary sulcus placement technique to manage refractive surprise. Case Presentation: A female patient aged 70 years reported experiencing blurred vision in her right eye (RE) for the past two years. History of RE cataract surgery ten years ago, however, she only had control 1-2 times after surgery. After that, the patient underwent cataract surgery on the left eye (LE), and then she complained that her RE was getting blurry. Her RE's visual acuity (VA) was 1/60 with best corrected visual acuity (BCVA) S-8.00 C-1.00 X100° to 6/10, and her LE was 7/10 with BCVA C-0.75 X60° to 10/10. The anterior segment examination of the RE was a 3-piece sulcus intraocular lens with complete continuous curvilinear capsulorhexis (CCC) intact anterior capsule, posterior capsule rupture, and the LE was in the bag IOL. Ultrasound examination of the RE revealed posterior staphyloma. She was diagnosed with OD refractive surprise, pseudophakia, posterior staphyloma, and OS pseudophakia. She underwent IOL exchange surgery on her RE. Post-operatively, the visual acuity of the RE was 7/45 using the Snellen chart. Three months post-op, the BCVA of RE was 10/10. Conclusions: In well-prepared cataract surgery, unexpected refractive outcomes such as a refractive surprise can be prevented. IOL exchange with ciliary sulcus placement technique is a treatment option for refractive surprise associated with posterior capsule rupture, and it has a good outcome.

Posterior capsular opacification and YAG laser capsulotomy in uveitis patients following cataract surgery

ObjectiveTo evaluate the incidence of visually significant posterior capsule opacification (PCO with visual acuity ≤20/50) and the incidence of Nd:YAG laser capsulotomy in the year following cataract surgery for uveitic eyes. MethodPatients were identified from the Systemic Immunosuppressive Therapy for Eye Diseases (SITE) Cohort Study using a standardized chart review process. ResultsAmong 1,855 uveitic eyes of 1,370 patients who had undergone cataract surgery, visually significant PCO occurred in 297 eyes (16%), and YAG laser capsulotomy was done in 407 eyes (22%) within the first year following surgery. Higher odds of developing 20/50 visual acuity attributed to PCO were noted in children and young adults compared with adults older than 65 years of age (overall p = 0.03). Poorer preoperative visual acuity (overall p = 0.0069) and postoperative inflammation (odds ratio [OR] = 1.83; 95% CI, 1.37–2.45; p < 0.0001) were associated with PCO incidence. In multivariable analysis, risk factors for YAG laser capsulotomy were younger age groups compared with those older than 65 years of age at the time of surgery (adjusted OR [aOR] = 1.90–2.24; 95% CI, 1.90–2.24; overall p = 0.0007), female sex (aOR = 1.37; 95% CI, 1.03–1.82; p = 0.03), postoperative active inflammation (aOR = 165; 95% CI, 1.27–2.16; overall p < 0.0001), extracapsular cataract extraction compared with phacoemulsification (aOR = 1.70; 95% CI, 1.17–2.47; overall p < 0.0001), and insertion of an intraocular lens (aOR = 4.60; 95% CI, –2.29–9.25; p < 0.0001). Black race was associated with lower YAG laser capsulotomy incidence than Whites (aOR = 0.36; 95% CI, 0.24–0.52; overall p < 0.0001). ConclusionsVision-reducing (≤20/50) PCO is common, occurring in about one sixth of uveitic eyes within 1 year of cataract surgery; a higher number (22%) of eyes underwent YAG laser capsulotomy within the first year. Age and postoperative inflammation following cataract surgery are the variables most associated with the incidence of visually significant PCO and YAG laser capsulotomy.

Management of Late Onset Sequential Pseudophakic Malignant Glaucoma: A Case Report and Review of Literature

Introduction: Malignant glaucoma or aqueous misdirection syndrome (AMS) can present in the immediate post-operative period or even many years after cataract surgery. We report the clinical course and management of a patient who developed the disease in both eyes at different time intervals after uneventful cataract surgery.Patient and Clinical Findings: A 76-year-old man developed diffusely shallow anterior chamber (AC) and high intraocular pressure (IOP) in his right eye after 2 years of pseudophakia, which did not resolve with laser peripheral iridotomy. A similar episode happened in left eye after 3 years of cataract surgery in the presence of a patent laser iridotomy.Diagnosis, Interventions, and Outcome: Shallow anterior chamber in the presence of a patent PI and normal posterior segment confirmed the diagnosis. The right eye was successfully managed with Nd:YAG laser capsulo-hyaloidotomy and pharmacotherapy, whereas in left eye, pars plana vitrectomy (PPV) with irido-zonulo-anterior hyaloidectomy (IZH) was done. Recurrence was noted after PPV also, owing to blockage of surgical iridectomy, which was treated with Nd:YAG laser.Conclusion: Pseudophakic malignant glaucoma can present many years after cataract surgery. Pars plana vitrectomy with IZH is an effective mode of treatment for refractory cases. Laser capsulo-hyaloidotomy may be more useful in the acute phase of the disease.

Risk Ractors for Strabismus Surgery after Pediatric Cataract Surgery in the United States.

To determine the cumulative incidence of strabismus surgery after pediatric cataract surgery and identify the associated risk factors. US population-based insurance claims retrospective cohort study. Patients ≤ 18 years old who underwent cataract surgery in 2 large databases: Optum Clinformatics Data Mart (2003-2021) and IBM MarketScan (2007-2016). Individuals with at least 6 months of prior enrollment were included, and those with a history of strabismus surgery were excluded. The primary outcome was strabismus surgery within 5 years of cataract surgery. The risk factors investigated included age, sex, persistent fetal vasculature (PFV), intraocular lens (IOL) placement, nystagmus and strabismus diagnoses before cataract surgery, and cataract surgery laterality. Kaplan-Meier estimated cumulative incidence of strabismus surgery 5 years after cataract surgery and hazard ratios (HRs) with 95% confidence intervals (CIs) from multivariable Cox proportional hazards regression models. Strabismus surgery was performed on 271/5822 children included in this study. The cumulative incidence of strabismus surgery within 5 years after cataract surgery was 9.6% (95% CI, 8.3%-10.9%). Children who underwent strabismus surgery were more likely to be of younger age at the time of cataract surgery, of female sex, have a history of PFV or nystagmus, have a pre-existing strabismus diagnosis, and less likely to have an IOL placed (all P < 0.001). Factors associated with strabismus surgery in the multivariable analysis included age 1 to 4 years (HR, 0.50; 95% CI, 0.36-0.69; P < 0.001) and age > 5 years (HR, 0.13; 95% CI, 0.09-0.18; P<0.001) compared with age < 1 year at time of cataract surgery, male sex (HR, 0.75; 95% CI, 0.59-0.95; P<0.001), IOL placement (HR, 0.71; 95% CI, 0.54-0.94; P= 0.016), and strabismus diagnosis before cataract surgery (HR, 4.13; 95% CI, 3.17-5.38; P < 0.001). Among patients with strabismus diagnosis before cataract surgery, younger age at cataract surgery was the only factor associated with increased risk of strabismus surgery. Approximately 10% of patients will undergo strabismus surgery within 5 years after pediatric cataract surgery. Children of younger age, female sex, and with a pre-existing strabismus diagnosis undergoing cataract surgery without IOL placement are at greater risk. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Incidence and Risk Factors for Retinal Detachment and Retinal Tear after Cataract Surgery: IRIS® Registry (Intelligent Research in Sight) Analysis

To report the incidence of and evaluate demographic, ocular comorbidities, and intraoperative factors for rhegmatogenous retinal detachment (RRD) and retinal tear (RT) after cataract surgery in the American Academy of Ophthalmology IRIS® Registry (Intelligent Research in Sight). Retrospective cohort study. Patients aged ≥ 40 years who underwent cataract surgery between 2014 and2017. Multivariable logistic regression was used to evaluate demographic, comorbidity, and intraoperative factors associated with RRD and RT after cataract surgery. Incidence and risk factors for RRD or RT within 1 year of cataract surgery. Of the 3 177 195 eyes of 1 983 712 patients included, 6690 (0.21%) developed RRD and 5489 (0.17%) developed RT without RRD within 1 year after cataract surgery. Multivariable logistic regression odds ratios (ORs) showed increased risk of RRD and RT, respectively, among men (OR 3.15; 95% confidence interval [CI], 2.99-3.32; P < 0.001 and 1.79; 95% CI, 1.70-1.89; P < 0.001), and younger ages compared with patients aged > 70, peaking at age 40 to 50 for RRD (8.61; 95% CI, 7.74-9.58; P < 0.001) and age 50 to 60 for RT (2.74; 95% CI, 2.52-2.98; P < 0.001). Increased odds of RRD were observed for procedure eyes with lattice degeneration (LD) (10.53; 95% CI, 9.82-11.28; P < 0.001), hypermature cataract (1.61; 95% CI, 1.06-2.45; P= 0.03), complex cataract surgery (1.52; 95% CI, 1.4-1.66; P < 0.001), posterior vitreous detachment (PVD) (1.24; 95% CI, 1.15-1.34; P < 0.001), and high myopia (1.2; 95% CI, 1.14-1.27; P < 0.001). Lattice degeneration conferred the highest odds of RT (43.86; 95% CI, 41.39-46.49; P < 0.001). In the IRIS Registry, RRD occurs in approximately 1 in 500 cataract surgeries in patients aged > 40 years within 1 year of surgery. The presence of LD conferred the highest odds for RRD and RT after surgery. Additional risk factors for RRD included male gender, younger age, hypermature cataract, PVD, and high myopia. These data may be useful during the informed consent process for cataract surgery and help identify patients at a higher risk of retinal complications. The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Risk Factors for Retinal Detachment RepairAfter Pediatric Cataract Surgery inthe United States.

To determine the cumulative incidence of retinal detachment (RD) repair following pediatric cataract surgery and identify the associated risk factors. US population-based insurance claims retrospective cohort study. Patients ≤ 18 years old who underwent cataract surgery in 2 large databases: Optum Clinformatics (2003-2021) and IBM MarketScan (2007-2016). Individuals with ≥ 6months of prior enrollment were included, and those with a history of RD, RD repair, traumatic cataract, spherophakia, or ectopia lentis were excluded. The primary outcome was time between initial cataract surgery and RD repair. The risk factors investigated included age, sex, persistent fetal vasculature (PFV), prematurity, intraocular lens (IOL) placement, and pars plana lensectomy approach. Kaplan-Meier estimated cumulative incidence of RD repair 5years after cataract surgery and hazard ratios (HRs) with 95% confidence intervals (CIs) from multivariable Cox proportional hazards regression models. Retinal detachment repair was performed on 47 of 3289 children included in this study. The cumulative incidence of RD repair within 5years of cataract surgery was 2.0% (95% CI, 1.3%-2.6%). Children requiring RD repair were more likely to have a history of prematurity or PFV and less likely to have an IOL placed (all P<0.001). Factors associated with RD repair in the multivariable analysis included a history of prematurity (HR, 6.89; 95% CI, 3.26-14.56; P < 0.001), PFV diagnosis (HR, 8.20; 95% CI, 4.11-16.37; P < 0.001), and IOL placement (HR, 0.44; 95% CI, 0.21-0.91; P=0.03). Age at surgery, sex, and pars plana lensectomy approach were not significantly associated with RD repair after adjusting for all other covariates. Approximately 2% of patients will undergo RD repair within 5years of pediatric cataract surgery. Children with a history of PFV and prematurity undergoing cataract surgery without IOL placement are at the greatest risk.

Risk of developing glaucoma-related adverse event within five years following pediatric cataract surgery

Children aged 0 to <13 years undergoing lens removal were enrolled into a prospective registry. We report the incidence of glaucoma/glaucoma suspect (“glaucoma-related adverse events”) within 5 years of cataract surgery and associated risk factors.

Capsaicin attenuates TGFβ2-induced epithelial-mesenchymal-transition in lens epithelial cells in vivo and in vitro

Posterior capsule opacification (PCO), the most common complication of cataract surgery occurring in 20–50% of patients after 2–5 years of cataract surgery, is a major problem in the aging society. The epithelial-mesenchymal transition (EMT) of lens epithelial cells after cataract surgery has been proposed as a major cause of PCO. Capsaicin, widely used as a food additive and analgesic agent, is a major pungent ingredient in red pepper. Although the effect of capsaicin on EMT has been reported in cancer cells, the biological reaction of capsaicin was unique in each cell type, and there have been no reports describing its effects on EMT earlier. In this study, we demonstrated that treatment with capsaicin inhibited TGFβ2-induced EMT in vitro lens epithelial cells and ex vivo explant lens epithelial cells. Furthermore, eye drops of capsaicin inhibited the PCO model mice in vivo. Finally, we showed that capsaicin inhibited non-canonically induced Smad2/3 activation via suppression of EGFR activation and ERK phosphorylation. Our findings indicate that capsaicin and its derivatives are good candidate compounds for preventing PCO after cataract surgery.

Capsular Bag Distention Syndrome after 9 years of Cataract Surgery

A 65-year-old male presented with complaints of foggy vision and glare in the right eye since 2 months. He had an uneventful cataract surgery in the right eye 9 years back and in the left eye 4 years back following which he had gained a visual acuity of 6/9 in both eyes. On examination his distance visual acuity was 6/12 in the right eye. Slit-lamp examination shows a peripheral soemmering ring and on careful inspection of the right eye posterior-chamber intraocular lens (PCIOL), a yellow-whitish turbid fluid collection was observed (Figure A).

A Population-Based Study of Anterior Ischemic Optic Neuropathy Following Cataract Surgery

To determine if there is an increased incidence rate of post-cataract surgery (pcs) anterior ischemic optic neuropathy (AION) compared to spontaneous AION (sAION). Retrospective, population-based cohort. Patients diagnosed with AION from January 1, 1990, through December 31, 2016, while residing in Olmsted County, Minnesota. Patients with cataract surgery preceding AION were included in the pcsAION cohort defined in 2 ways: AION within 2months and AION within 1 year of cataract surgery. The incidence rates of pcsAION and sAION were compared using Poisson regression models. During the study period, 102 residents developed AION. The median age was 65 years (range, 40-90 years), 44 (43.1%) were female. Twenty of 102 (19.6%) patients had previous cataract surgery, of which 2 and 9 developed AION within 2months and 1 year of surgery, respectively. The annual incidence rate of pcsAION within 2months of surgery (8.6 per 100,000) was not significantly greater than the annual incidence rate of sAION (6.9 per 100,000; P= .78). However, the annual incidence rate of pcsAION within 1 year of surgery (38.9 per 100,000) was significantly higher than the incidence rate of sAION (6.5 per 100,000; P < .001). The incidence of AION is increased in the first year after cataract surgery, but not in the early (i.e., 2months) postoperative period.

Eleven Years of Cataract Surgery in Veterans Without Pre-existing Ocular Comorbidities.

In 2017, over 75,000 cataract surgeries were performed within the Veterans Health Administration System (VHA). Previous reports of outcomes of cataract surgery in veterans include patients with pre-existing ocular disease, which can affect vision. To exclude the confounding factor of pre-existing ocular comorbidities, we investigated the long-term visual outcomes and complications associated with small incision cataract surgery performed on veterans without any pre-existing eye disease. Institutional Review Board approved cohort study with detailed retrospective chart review of all phacoemulsification (small incision) cataract surgeries performed at the Veterans Affairs Medical Center in Washington D.C. over 11 years, including all pre-and postoperative visits until postoperative month 12. A total of 1,513 consecutive surgical cases without any pre-existing ocular disease except the cataract were included. Vision improved significantly after cataract surgery compared to the preoperative best-corrected visual acuity (BCVA) (p = 0.0001) and remained stable over the first intra- and postoperative year. All eyes without complicated surgery and 99.1% of eyes with complications achieved 20/40 or better final vision postoperatively. The most common intra-and postoperative complications were vitreous loss (3.1%) and cystoid macular edema (CME; 1.4%). Patients with complications achieved final mean BCVA of 0.04 (20/22, vitreous loss) and 0.06 (20/23, CME) mean logMAR (Snellen). Analysis of 11 years of small incision cataract surgery in eyes without pre-existing ocular disease within the VHA showed significant improvement in vision and stability 12 months after uncomplicated and complicated surgery in veterans.

A rare case of polymethylmethacrylate intraocular lens opacity

Optical transparency of the intraocular lens (IOLs) is paramount in maintaining visual improvement after cataract extraction. There have been reports of the IOL developing opacity after years of cataract surgery. IOL opacities have been reported in silicone, acrylic lens, and very rarely in polymethylmethacrylate (PMMA) IOLs. Though the exact cause is not known, long-term exposure to ultraviolet light can be one of the most probably causes, leading to disruption of PMMA and release of gaseous (nitrogen) within the PMMA substance. We report one such rare case of PMMA IOL opacity in a 75-year-old female.

Liquefied after cataract and its surgical treatment.

Aims:To describe liquefied after cataract (LAC) and its surgical management following an uneventful phacoemulsification with posterior chamber in-the-bag intraocular lens (IOL) implantation and continuous curvilinear capsulorrhexis (CCC).Design:Interventional case series.Materials and Methods:Eleven patients with LAC, following uneventful phacoemulsification with CCC and in-the-bag IOL implantation were enrolled. After the basic slit lamp examination, each case was investigated with Scheimpflug photography and ultrasound biomicroscopy (UBM). Each case was treated with capsular lavage. Biochemical composition of the milky fluid was evaluated and ring of anterior capsular opacity (ACO) was examined under electron microscope.Results:All 11 cases presented with blurring of vision after 6-8 years of cataract surgery with IOL implantation. All cases had IOL microvacuoles, 360° anterior capsule, and anterior IOL surface touch along with ACO, ring of Soemmering, and posterior capsule distension filled with opalescent milky fluid with whitish floppy or crystalline deposits. Biochemically, the milky fluid contained protein (800 mg/dl), albumin (100 mg/dl), sugar (105 mg/dl), and calcium (0.13%) and was bacteriologically sterile. Histologically, the dissected ACO showed fibrous tissue. All cases were successfully treated with capsular lavage with good visual recovery and with no complication. There was no recurrence of LAC during 2 years postoperative follow-up in any of the cases.Conclusions:LAC is a late complication of standard cataract surgery. It may be a spectrum of capsular bag distension syndrome (CBDS) without shallow anterior chamber and secondary glaucoma. Capsular bag lavage is a simple and effective treatment for LAC and a safe alternative to neodymium-doped yttrium aluminum garnet (Nd-YAG) capsulotomy.

Cataractogenesis and surgical outcome in patients with uveitis

AbstractPurpose To compare the risk of cataract development, the surgical management and the prevalence of complications in 2 groups of patients with uveitis treated in 2000 and 2010.Methods Retrospective study of patients with uveitis referred to an academic centre for the diagnosis and treatment of uveitis. An extensive work‐up based on clinical presentation was performed when necessary. Corticosteroids were the mainstay of therapy in 2000 but new immunosuppressive molecules and biologics were used in 2010. Two groups were analyzed based on the year of cataract surgery (group A:2000 and group B:2010). Demographic factors, delay between onset of uveitis and cataract surgery, improvement of visual acuity and major complications were studied. Phacoemulsification and intraocular lens implantation were performed in all cases respecting a 3‐month quiescence of uveitis and an efficient perioperative anti‐inflammatory regimen.Results The study included 125 eyes of 107 patients. 59 eyes (48 patients: F/M: 1.29) were operated in 2000 (group A) and 66 (59 patients: F/M: 1.5) in 2010 (group B). An associated condition was determined in 81 cases (75.5 %): mainly herpetic uveitis (9), sarcoidosis (7), tuberculosis (10), birdshot chorioretinopathy (7), Behcet's disease (8), spondyloarthropathy (10), Vogt‐Koyanagi‐Harada disease (5), Fuchs heterochromic iridocyclitis (8). Delay between onset of uveitis and surgery was 58.86 months in group A and 111.68 months in group B (p&lt;0.01). Mean BCVA postoperatively improved from logMAR 0.927 and 0.731 to 0.439 and 0,242 in groups A and B, respectively.Conclusion During a 10‐year period, management of uveitis has dramatically improved. Better management of ocular inflammation based on biologic agents may delay cataractogenesis in active patients.

Real-time Polymerase Chain Reaction in the Diagnosis of Acute Postoperative Endophthalmitis

To evaluate the efficacy of quantitative real-time polymerase chain reaction (qPCR) in the diagnosis of postoperative bacterial endophthalmitis among patients who underwent cataract surgery at a tertiary care center. Prospective experimental study. This was a single-center study of 64 eyes of 64 patients presenting with clinical signs and symptoms of endophthalmitis within 1 year of cataract surgery. Patients with glaucoma filtering or cornea surgery in the past year, postoperative trauma, fungal endophthalmitis, or preoperative inflammatory conditions were excluded. Vitreous samples were obtained during vitreous tap or vitrectomy and sent for both culture and qPCR with sequencing. Vitreous samples obtained from 50 patients undergoing vitrectomy for noninflammatory indications served as controls. The main outcome measures were the sensitivity of qPCR compared to culture and concordance of results of pathogen identification with sequencing vs phenotypic speciation. qPCR detected 16s bacterial DNA in 37 patients (66%), compared to 19 (34%) with traditional culture. Only 1 patient had a positive result by culture (Nocardia species) but negative result by qPCR. For the 18 samples positive by both qPCR and culture, there was a 100% concordance in pathogen identification between sequencing and phenotypic speciation. In cases of suspected bacterial endophthalmitis, qPCR offers an improved diagnostic yield and may be a useful adjunct to traditional culture. Further large-scale clinical studies are needed to elucidate the full clinical utility of qPCR.

Indications and techniques of penetrating keratoplasties, 1985-1988.

Indications and surgical techniques for penetrating keratoplasties (PKs) were evaluated to determine present trends and suggest future directions for PK. Analyses were based on 3,941 PK cases, with questionnaires completed at the time of surgery by 638 surgeons receiving tissue through Tissue Banks International, Inc. between July 1, 1985, and December 31, 1988. The leading indications for PK were pseudophakic corneal edema (PCE) (23%), graft failure (17%), Fuchs' corneal dystrophy (13%), kerataconus (13%), keratitis/scar (12%), and aphakic corneal edema (10%). Indications for PK varied by age and sex. Anterior chamber (AC) lenses accounted for the majority (56%) of PCE cases. Penetrating keratoplasty for PCE occurred within 5 years of cataract surgery for 81% of patients with PC lenses and only 52% of patients with AC lenses. Intraocular lens exchange was performed in most AC and iris-fixed lens PCE cases (65% and 77%, respectively), but less frequently in PC lens cases (17%). A PC lens was placed in 29% of all PCE lens exchange cases. These data have confirmed and expanded observations from smaller studies about leading indications and surgical techniques for PK. Therefore, eye bank data may be useful in describing and monitoring future indications and trends for PK because they provide a broader base of information than that obtained through a single institution.

Retinal tears and detachments after extracapsular cataract surgery

A review of 3,120 consecutive cases of extracapsular cataract extraction revealed a retinal detachment incidence of o. S% and a retinal tear incidence of 0.9%. Approximately 85% of all tears and detachments occurred within the first three years of cataract surgery. Analysis of the retinal detachment group identified several risk factors. These included young age, male sex, axial length greater than 25 mm, primary posterior capsulotomy, and previous retinal surgery in the fellow eye. In the retinal tear group, the risk factors were young age and previous retinal surgery in the fellow eye. Visual results were excellent with an average of one line of acuity lost after successful macula-on and macula-off detachment surgery 'and no significant change after retinal tear repair. Despite multiple surgeries, the retinas in two detachments were lost to proliferative vitreoretinopathy.

Retinal detachment in the second eye.

Bilateral retinal detachment (RD) occurred in 13% of 737 patients, with an interval between detachments of up to 30 years. Bilateral RD was more common in male patients and in those having more than 3 diopters of myopia. Detachment in the second eye was caused by retinal breaks in previously observed degeneration in 43% and in unsuspected diseased retina 57%. A significant number of patients with bilateral RD had multiple breaks. Aphakic RD occurred in bilateral RD and in unilateral RD patients at a comparable frequency; 28% of bilateral (mean duration, four years) and 35% of unilateral aphakic RDs occurred within one year of cataract surgery. Symptoms from retinal breaks were not reliable prognostic factors; only 39% of patients had warning before RD. Patients with bilateral RD had more reoperations with fewer successes, factors suggesting greater severity than unilateral RD.