Full panretinal photocoagulation and early vitrectomy improve prognosis of florid diabetic retinopathy

BACKGROUND

Florid diabetic retinopathy (FDR) is a rare form of proliferative diabetic retinopathy (PDR) that is characterized by a bilateral rapidly progressive, very severe ischemic retinopathy. Florid diabetic retinopathy was reported to carry a high risk of blindness. This study was conducted to determine whether visual prognosis of FDR can be improved by appropriate photocoagulation and surgical management.

METHODS

The authors retrospectively studied 20 patients (40 eyes) who were treated from October 1978 to February 1994. Systemic risk factors, visual acuity, complete ocular examination, and fundus findings, as well as fluorescein angiography, were analyzed with respect to photocoagulation and surgical management. Mean follow-up was 3.6 years.

RESULTS

All patients had poorly controlled type I diabetes (mean duration, 13.5 years), which often was associated with systemic complications. Mean initial visual acuity was equal to or better than 20/40 in 32 eyes (80%). During the course of the study, high-risk PDR was observed in 38 eyes (95%) and vitreous hemorrhage occurred in 26 eyes (65%). Extensive full subconfluent panretinal photocoagulation was performed completely in 37 eyes (92.5%). Vitrectomy was necessary in 15 eyes (37.5%). Macular edema was present in 30 eyes (75%). Major complications included retinal detachment that required surgery (2 eyes, 5%) and neovascular glaucoma (2 eyes, 5%). However, final visual acuity was equal to or better than 20/40 in 23 eyes (57.5%) and less than 5/200 in only 4 eyes (10%).

CONCLUSION

These results suggest that aggressive treatment of FDR with extensive panretinal photocoagulation and early vitrectomy, when necessary, may result in a much better prognosis than has been reported previously.

Initial clinical experience with an erbium:YAG laser for vitreoretinal surgery

PURPOSE

We tested the efficacy of an erbium:YAG laser for maneuvers in patients undergoing vitreoretinal surgery.

METHODS

An erbium:YAG laser equipped with a flexible fiberoptic and interchangeable 20-gauge endoprobes of various tip configurations ranging from 100 to 365 microns was used for specific maneuvers in 13 patients referred for vitreoretinal surgery for diabetic traction detachment, proliferative vitreoretinopathy, retinal detachment with posterior break, and epimacular membrane. The following maneuvers were performed: (1) transection of elevated vitreous membranes, (2) incision of epiretinal membranes, (3) drainage and relaxing retinotomy, (4) transection of subretinal membranes, (5) noncontact ablation of epiretinal membranes in air-filled eyes, (6) ablation of lens remnants, (7) posterior capsulotomy, (8) iris surgery, and (9) retinal vascular coagulation.

RESULTS

Forty-eight defined maneuvers were performed with energy levels ranging from 0.2 to 5.0 mJ and repetition rates of 2 to 30 Hz. Transection of elevated membranes, subretinal membranes, and retinotomies were easily performed. Fourteen incisions into vascularized epiretinal membranes in diabetic traction detachment surgery demonstrated a fine margin of coagulation that permitted hemostatic incision. Retinal breaks were created during one of these incisions. Lens remnant ablation, posterior capsulotomy, and iris tissue removal were successful, with a single complication consisting of damage to the posterior surface of an intraocular lens during a pars plana posterior capsulotomy accomplished by means of a side-firing probe. Epiretinal membrane ablations in air-filled eyes were effectively performed in a gradual fashion without hemorrhage.

CONCLUSIONS

The erbium:YAG laser offers precise and effective tissue cutting and removal in vitreoretinal maneuvers. Further study will determine the role of this technology in vitreoretinal surgery.

Vitrectomy for diabetic macular edema associated with a thickened and taut posterior hyaloid membrane

PURPOSE

To evaluate the surgical results in a series of patients with diabetic macular edema associated with traction from a thickened and taut posterior hyaloid membrane and to identify features associated with better visual outcome.

METHODS

We reviewed the clinical records of ten consecutive patients who underwent pars plana vitrectomy in one eye for diabetic macular edema that was preoperatively attributed to thickening and traction of the posterior hyaloid membrane.

RESULTS

Best-corrected, preoperative visual acuity was 20/200 in seven eyes, 20/300 in one eye, and 20/400 in two eyes. Intraoperatively, seven patients were found to have an attached posterior hyaloid membrane which was thickened and taut. Among these seven patients, postoperative best-corrected visual acuity improved by six lines in two eyes, by five lines in one eye, by two lines in one eye, and remained within one line of preoperative visual acuity in three eyes. The other three patients had an epiretinal membrane simulating an attached and thickened posterior hyaloid membrane.

CONCLUSIONS

Vitrectomy effectively improved visual acuity in some eyes with diabetic macular edema associated with traction from a thickened and taut posterior hyaloid membrane. Despite careful preoperative examination with a fundus contact lens, however, in some patients it may be difficult to assess how the posterior hyaloid membrane contributes to the macular edema. In selected patients, early surgical intervention may be associated with better visual outcome.

The importance of early diagnosis of treatable diabetic retinopathy for the four-year visual outcome in older-onset diabetes mellitus

The four-year visual outcome was retrospectively studied in patients with older-onset diabetes mellitus and diabetic retinopathy in need of laser treatment. Visual acuity in 53 patients examined by ophthalmologists who referred the patients for an evaluation of retinopathy before laser treatment, was compared to that of 47 patients examined by ophthalmologists who also performed the photocoagulation. The number of eyes that became blind (visual acuity < or = 6/60) during the four-year period was higher (23/90 vs 9/91; p < 0.01) among referred patients, whereas the number of retinal examinations per patient during the three-year period prior to laser treatment did not differ between the two groups. Among referred patients, 13% had not been ophthalmologically examined before the treatment-requiring retinopathy was found. Corresponding figure for those examined at the laser centre was 23%. Severe macular oedema in regularly examined patients was more common among referred patients (9/30 vs 1/32; p < 0.01). The results indicate that screening for diabetic retinopathy in older-onset diabetes was not performed satisfactorily. In addition, laser treatment was delayed in older-onset diabetic patients controlled by ophthalmologists who referred patients for photocoagulation, resulting in an increased incidence of legally blind eyes. The study also stresses the importance of carrying out knowledge of when and how to diagnose early sight-threatening diabetic retinopathy to ophthalmologists referring patients for laser treatment.

[Intraocular silicone oil tamponade. A clinico-pathologic study of 36 enucleated eyes]

BACKGROUND

Previous histological studies have shown that intraocular silicone oil induces irreversible changes in ocular tissues, especially the retina. The purpose of this study was to analyze, in a larger group of enucleated eyes, changes in intraocular tissue after silicone oil injection, dependent on intraocular pressure, how long the oil was in the eye, and the viscosity of intraocular silicone oil.

PATIENTS AND METHODS

We did histological examinations on 36 enucleated globes with intraocular silicone oil after vitreoretinal surgery and compared them with 68 enucleated globes treated with buckle and encircling band using immunohistochemistry (n = 5) and electron microscopy (n = 7). For statistical evaluation we used the chi(2) test and analysis of variance.

RESULTS

After silicone oil injection we observed a more pronounced reduction in corneal endothelial cells (58%), more frequent closed chamber angle (86%), atrophy of the ciliary body (80%) (P < 0.05), proliferative vitreoretinopathy (89%), and glaucomatous atrophy of the optic nerve (56%) (P < 0.01). The retinae showed independent of the use of silicone oil a loss of inner and outer segments of photoreceptors and of ganglion cells and thinning and rareficaton of all other retinal layers. Globes with silicone oil revealed vacuoles both free and incorporated by macrophages in all layers of the retina. Similar vacuoles were seen in the optic nerve, choroid, retinal pigment epithelium, ciliary body, iris, chamber angle and the corneal endothelium. Silicone oil vacuoles were seen in the retina and optic nerve by 1 month after surgery in two eyes with high intraocular pressure (42 mmHg). Six of eight eyes with normal intraocular pressure levels showed retinal vacuoles, 3 of them after 2 months. Vacuoles in the optic nerve were found in eight of nine eyes with intraocular instillation of 1000 mPa silicone oil. There was no clinicohistopathological correlation between the presence of vacuoles in the retina or optic nerve and the duration and viscosity of intraocular silicone oil.

CONCLUSIONS

This study suggests that vacuoles in eyes with silicone oil instillation can be found in the retina after 4 weeks. The period of intraocular silicone oil should be limited to 3-6 months.

[Endolaser photocoagulation in vitrectomy surgery]

OBJECTIVE

To verify the usefulness and effectiveness of endolaser photocoagulation in vitrectomy.

METHODS

Endolaser photocoagulation was applied in 40 cases (45 eyes) of vitrectomy surgery. Indications for vitrectomy included vitreous hemorrhage 31 eyes (proliferative diabetic retinopathy 13, Eales's disease 13, retinal vein occlusion 4, and scleral penetrating injury with intraocular foreign body removal 1), complex retinal detachment 12 eyes, intraocular nonmagnetic foreign body removal and postoperative silicone oil tamponade 1 eye respectively. Treatment involved pan-retinal scatter therapy in 7 eyes, focal therapy in 22 eyes, sealing primary or iatrogenic retinal breaks in 14 eyes, draining retinotomy in 2 eyes, and encircling scleral buckle photocoagulation in 3 eyes. The follow-up times ranged from 2 to 18 months (average 9 months).

RESULTS

Whitening of laser spots was not apparent in 6 eyes with retinal breaks following incomplete gas-fluid exchange. Recurrent retinal detachments occurred in 5 eyes postoperatively.

CONCLUSION

Endolaser photocoagulation facilitates the performance and reduces the complications of vitrectomy surgery.

Partial characterization of a putative new growth factor present in pathological human vitreous

BACKGROUND

Several growth factors have been implicated in the development of proliferative eye diseases, and some of those are present in human vitreous (HV). The effects of HV on cellular responses which modulate proliferative cell processes were studied. This study describes the partial characterization of a vitreous factor activity which does not correspond to any of the previously reported growth factors in pathological HV.

METHODS

Vitreous humour was obtained from medical vitrectomies, from patients with PDR and PVR. The biological activity of the vitreous factor was determined by its ability to increase cytosolic calcium concentration ([Ca2+]i), increase production of inositol phosphates, and induce cell proliferation in the cell line EGFR T17. In some experiments other cell lines, such as NIH 3T3, 3T3-L1, FRTL5, A431, PC12, Y79, and GH3, were also employed. Measurement of [Ca2+]i in cell suspensions was performed using the fluorescent Ca2+ indicator fura-2. The activity of the factor present in HV was compared with other growth factors by means of: (a) [Ca2+]i mobilization pattern, (b) sequential homologous and heterologous desensitization of receptors, (c) effects of phorbol esters on their action, and (d) inactivation after treatment with different proteolytic enzymes.

RESULTS

The HV-induced cell proliferation and increases in [Ca2+]i concentration were characterized by a peculiar time pattern. The different approaches used ruled out its identity with PDGF, bFGF, EGF, TGF-beta, IGFs, TNF-alpha, NGF, and other compounds such as ATP, angiotensin I, and bradykinin. Vitreous factor actions are mediated by specific receptors apparently regulated by PKC. This factor is able to induce [Ca2+]i mobilization in most of the cell lines studied, indicating that its effects are not tissue specific.

CONCLUSIONS

These results suggest the presence of a growth factor activity in pathological HV which may be due to the presence of an undescribed growth factor in the eye.

[Retinal hemodynamics in diabetic retinopathy before and after laser coagulation]

PATIENTS AND METHODS

By means of video-fluoresce in angiography arm-retina-time (ART) and retinal arteriovenous passage time (AVP) were measured in order to determine the effect of panretinal laser-coagulation on retinal circulation in patients with diabetic retinopathy. 55 patients with either preproliferative (n = 29) or proliferative (n = 26) retinopathy we reexamined before, 3-9 weeks after panretinal laser-coagulation (mean: 848 burns, 0.5 mm diameter), and 0.5-3 years later.

RESULTS

The ART of the diabetic patients was in the normal range and showed no differences among the three measuring times. The retinal AVP was significantly prolonged in the three measuring times (nasal and temporal) when compared to normals. Laser-coagulation showed no significant effect on AVP in the temporal branches, whereas in the nasal branches AVP decreased from 2.38 +/- 0.69 s (before laser-coagulation) to 2.11 +/- 0.68 s (3-9 weeks after treatment) and 2.06 +/- 0.67 s (0.5-3 years after treatment) (p < 0.01). In branches with neovascularisation (n = 24) a pronounced decrease of AVP from 2.60 +/- 0.70 s to 1.96 +/- 0.61 s and 2.09 +/- 0.64 s (p < 0.01) was detected.

CONCLUSIONS

Thus, laser-coagulation leads to a faster circulation in areas with laser burns within 3-9 weeks post-treatment.

Distribution of TNF alpha and its reactive vascular adhesion molecules in fibrovascular membranes of proliferative diabetic retinopathy

AIMS

This study investigated the presence of the cytokine tumour necrosis factor alpha (TNF alpha) and the vascular adhesion glycoproteins ICAM-1, VCAM-1, E-selectin, P-selectin, and PECAM within fibrovascular membranes of eyes with proliferative diabetic retinopathy (PDR).

METHODS

The presence of these molecules was determined by immunohistochemical staining using monoclonal antibodies and the APAAP technique.

RESULTS

Staining for TNF alpha was observed on the retinal vascular endothelium of five of 12 specimens, on infiltrating cells within all membranes, and on the extracellular matrix of nine specimens. This staining wa abolished by absorption of the monoclonal antibody with human recombinant TNF alpha. Likewise, ICAM-1 staining was given by infiltrating cells and extracellular matrix of nine membranes and by the endothelium of three of the specimens. VCAM-1, E-selectin, and P-selectin staining was observed on the vascular endothelium of 5/12, 4/12, and 3/12 epiretinal membranes respectively. PECAM was expressed by the endothelium of 4/12 specimens, by infiltrating cells of 8/12 membranes, and also by the extracellular matrix of two of the specimens.

CONCLUSION

The widespread distribution of TNF alpha and the nature of the adhesion molecules expressed by vascular endothelial cells in PDR membranes suggest that local activation of TNF alpha and enhanced expression of vascular cell adhesion molecules may play an important role in the development of the proliferative phase of diabetic retinopathy.

Vitrectomy in diabetic patients with a blind fellow eye

Results of pars plana vitrectomy for complications of proliferative diabetic retinopathy were analysed in 32 consecutive patients with a blind fellow eye due to diabetic eye disease. The mean follow-up period was 22.3 months. Only 16% of all eyes examined had received full scatter photocoagulation prior to referral for vitrectomy. Out of 9 eyes with vitreous haemorrhage, 8 improved to a visual acuity of > or = 0.2 postoperatively. Amid 23 eyes which were vitrectomized for advanced traction retinal detachment, only 4 eyes improved to a postoperative visual acuity of > or = 0.02. In this group 12 eyes deteriorated after vitrectomy, 3 eyes progressing to no light perception. The postoperative visual outcome after vitrectomy for traction retinal detachment in this group of diabetics with a blind fellow eye (mean postoperative visual acuity 0.03 +/- 0.05) was significantly worse (p < 0.000) compared to a group of 196 patients with a seeing fellow eye who were vitrectomized for traction retinal detachment at our clinic (mean postoperative visual acuity 0.09 +/- 0.11). Therefore we conclude that traction retinal detachment in this subgroup of patients is a particularly severe presentation of diabetic retinopathy with a guarded functional prognosis after vitrectomy. Our results demonstrate the importance of timely full scatter photocoagulation and early vitrectomy in eyes with progressive fibrovascular proliferation not responding to panretinal photocoagulation. We conclude that especially diabetic patients with a blind fellow eye must be followed closely and assigned to vitrectomy at an earlier stage of their disease in order to improve functional prognosis.

[Primary intraocular lens implantation after laser therapy in active diabetic retinopathy]

The author presents an account of the results and complications of cataract operations with primary implantation of a posterior chamber intraocular lens in 10 eyes of 8 patients suffering from preproliferative diabetic retinopathy, partly treated by laser. After operation in nine eyes the visual acuity improved during a mean follow-up period of 22.7 months. As to postoperative complications, a late fibrinous reaction was important (4x posterior synechia of the iris, incl. iris capture syndrome in one case with subsequent secondary glaucoma). In three eyes within one year secondary fibrotic cataract developed, in one it was necessary to perform Nd-YAG laser membranotomy. In none of the eyes so far after supplementary laser coagulation progression of diabetic retinopathy was recorded. The authors recommend to carry out maximum laser coagulation of the retina before operation of the cataract, to remove during operation the total mass of the lens, to carry out preventive basal iridectomy and to complete panretinal laser coagulation as quickly as possible after operation.

Double-frequency Nd:YAG laser vs. argon-green laser in the treatment of proliferative diabetic retinopathy: randomized study with long-term follow-up

BACKGROUND AND OBJECTIVE

A randomized clinical trial using the argon-green (514 nm) and the double-frequency Nd:YAG (532 nm) lasers was carried out on 42 eyes with proliferative diabetic retinopathy (PDR), with the aim of assessing the long-term effects of double-frequency Nd:YAG panretinal photocoagulation (PRP).

MATERIALS AND METHODS

Twenty-one eyes were randomized to argon laser treatment (ALT) and 21 to double-frequency Nd:YAG laser treatment (NdLT). The mean follow-up was 28.90 months (+/- 6.13) in the ALT group and 29.57 months (+/- 5.17) in the NdLT group.

RESULTS

In the ALT group, 20 eyes (95.2%) showed regression of PDR and one eye (4.8%) enlargement of pre-existing new vessels. In the NdLT group, neovascularization regressed in 20 eyes (95.2%) and increased in one (4.8%).

CONCLUSIONS

The long-term efficacy of double-frequency Nd: YAG laser PRP in the treatment of PDR thus appears to be similar to that of argon-green.

Timing of cataract surgery in diabetics

In their retrospective study, the authors investigated the outcome of extracapsular cataract extraction (ECCE) followed by posterior chamber intraocular lens implantation (PCIOL), in 2864 operated eyes, out of which 546 (19%) were in diabetics. The preoperative retinal status was recorded in all subjects. In 6 (1%) patients, laser photocoagulation was performed preoperatively. The obtained visual acuity was 0.4 or better in 90.0% of diabetics and in 91.8% of control subjects, showing no significant difference in the postoperative complications between diabetics and non-diabetics. The results indicated the cataract operation (ECCE + PCIOL) to be a well tolerated surgical procedure in diabetic patients with lenticular opacity, in whom it should be even earlier performed than in nondiabetics, because cataract prevents the diagnosis or treatment of a suspect retinal disorder.

Grid pattern photocoagulation for diabetic macular edema--long-term visual results

The authors reviewed the data of 226 eyes in 124 patients with clinically significant diabetic macular edema treated by grid pattern photocoagulation from 1986 to 1994 at the Ophthalmological Clinic of Innsbruck University Hospital. On the basis of baseline visual acuity (VA), eyes were classified in four groups: group 1 = VA < 0.1; group 2 = VA 0.1-0.2; group 3 = VA > 0.2-0.5; group 4 = VA > 0.5. The development of VA from the baseline examination until the last checkup in treated eyes is reported. This classification showed a better visual outcome after photocoagulation in eyes with a decreased VA at baseline (groups 1, 2) compared with eyes with a good initial VA (groups 3, 4). The difference in visual outcome between the second and third groups as well as between the third and fourth groups was statistically significant (p < or = 0.001). A correlation of initial VA with visual outcome after treatment was demonstrated (R = -0.558; p = 0.0001). Clinical conclusions of these results are discussed.

Development of an integrated automated retinal surgical laser system

Researchers at the University of Texas and the USAF Academy have worked toward the development of a retinal robotic laser system. The overall goal of this ongoing project is to precisely place and control the depth of laser lesions for the treatment of various retinal diseases such as diabetic retinopathy and retinal tears. Separate low speed prototype subsystems have been developed to control lesion depth using lesion reflectance feedback parameters and lesion placement using retinal vessels as tracking landmarks. Both subsystems have been successfully demonstrated in vivo on pigmented rabbits using an argon continuous wave laser. Preliminary testing on rhesus primate subjects have been accomplished with the CW argon laser and also the ultrashort pulse laser. Recent efforts have concentrated on combining the two subsystems into a single prototype capable of simultaneously controlling both lesion depth and placement. We have designated this combined system CALOSOS for Computer Aided Laser Optics System for Ophthalmic Surgery. Several interesting areas of study have developed in integrating the two subsystems: 1) "doughnut" shaped lesions that occur under certain combinations of laser power, spot size, and irradiation time complicating measurements of central lesion reflectance, 2) the optimal retinal field of view (FOV) to achieve both tracking and lesion parameter control, and 3) development of a hybrid analog/digital tracker using confocal reflectometry to achieve retinal tracking speeds of up to 100 dgs. This presentation will discuss these design issues of this clinically significant prototype system. Details of the hybrid prototype system are provided in "Hybrid Eye Tracking for Computer-Aided Retinal Surgery" at this conference. The paper will close with remaining technical hurdles to clear prior to testing the full-up clinical prototype system.

Falsely nonrecordable flash visual evoked cortical potentials in a diabetic eye with severe vitreous hemorrhage

The examination of visual evoked cortical potentials (VECPs) prior to vitrectomy has been proposed for selection of patients with good chances for a favorable outcome following surgery. A missing single flash VECP has been considered a contraindication for further surgical treatment. A 64-year-old woman with proliferative diabetic retinopathy suffered from an intensive vitreous hemorrhage in one eye. Preoperatively, the flash VECP was nonrecordable. Intraoperatively, a dense vitreous hemorrhage and retrohyaloidal blood was found. The retina was attached. Postoperatively, the flash VECP was similar in both eyes with normal latencies. The visual acuity improved from light perception to 0.05. Severe vitreous hemorrhage may interfere with preoperative VECP recordings. A nonrecordable VECP has to be judged cautiously so as to prevent false-negative responses in eyes that could regain vision following vitrectomy and removal of the hemorrhage.

[Evolution of blood glucose control and retinopathy during long-term treatment of insulin-dependent diabetes mellitus with intraperitoneal infusion of insulin]

To evaluate the efficacy on blood glucose control of long-term peritoneal insulin infusion and its consequences on the evolution of diabetic retinopathy, we analyzed retrospectively the values of glycosylated haemoglobin measured quarterly and the retinal angiograms obtained after 1, 5 and 9 years from seventeen insulin-dependent diabetic patients treated by this technique during 9.0 +/- 2.2 years. Blood glucose control was significantly improved from the first year of treatment (p < 0.01). Seventy-one per cent of patients had a level of glycosylated hemoglobin below one standard deviation of normal values after five years and ninety-two per cent of 12 patients treated up to nine years remained in the same near-normal range. Glycaemic excursions below 0.5 g/l and over 2 g/l were limited to 5-7% and 15-17% of four times-daily capillary glucose measurements respectively, along the whole IP insulin infusion period. Among 7 patients with no retinopathy (n = 1) or with mild to moderate nonproliferative retinopathy, requiring no specific ophthalmological treatment, (levels 20 to 40 on worse eye according to a simplified version of ETDRS classification, n = 6), 3 remained stable, 2 improved and 2 impaired although remaining under level 50 of the classification, after 5 to 9 years. Nine patients with severe nonproliferative (level 50, n = 1) or proliferative (level 65, n = 8) retinopathy, all treated by panretinal photocoagulation before initiation of IP treatment, improved and one patient with severe nonproliferative retinopathy, incompletely treated by laser photocoagulation, remained stable, after 5 to 9 years. No macular edematous reaction or impairment of existing macular edema occurred after panretinal photocoagulation under IP treatment. These data indicate that a sustained near-normal blood glucose control can be achieved under long-term peritoneal insulin infusion, without significant impairment of diabetic retinopathy when an initial ophthalmological evaluation, and a specific treatment if necessary, are performed.

Cost-benefit analysis of diabetic eye disease

Diabetic retinopathy is the main cause of blindness in adults 25-74 years of age in Western countries. At 100% diagnosability and 100% treatability, with laser photocoagulation vision can be retained in at least one eye in 73% of patients with proliferative retinopathy and in 67% of patients with diabetic maculopathy. The cost-benefit analysis draws a comparison of the costs incurred through benefits granted to a blind diabetic and those incurred through proper screening, examination and treatment to avoid blindness as much as possible. These calculations are valid for the State of Tyrol in Austria. The anticipated annual costs for blindness are thus ATS 19,000,000, of which ATS 14,600,000 could be avoided through an optimal screening, examination and therapy program. The maximum costs for examination and therapy amount to ATS 10,700,000, thus giving a minimum saving of ATS 3,900,000 in favor of preventive medicine.

Ocular blood flow velocities in patients with proliferative diabetic retinopathy after scatter photocoagulation. Two years of follow-up

PURPOSE

Color Doppler imaging allows for simultaneous two-dimensional anatomic imaging and Doppler measurement of blood flow velocity. Because hemodynamic changes have been seen in diabetic patients after photocoagulation by other techniques, the authors compared 25 eyes with proliferative diabetic retinopathy before, 6 months after, 1 year after, and 2 years after panretinal photocoagulation with a matched control group of 30 healthy volunteers (55 eyes).

METHODS

The ophthalmic artery, short posterior ciliary artery, central retinal vessels, and vortex veins of all patients were examined, and the systolic, and diastolic, and mean arterial velocities were measured. Panretinal photocoagulation was performed with these parameters: 800-1000 spots, 0.1 second, 500-microns argon laser.

RESULTS

Student's t test revealed that the perfusion velocity was significantly lower in diabetic patients than in healthy controls (V systolic in the ophthalmic artery: 31.7 +/- 6.7 cm/s vs. 36.6 +/- 7.0 cm/s, respectively, P = 0.03). After treatment, blood flow velocities were significantly lower than before photocoagulation (V systolic in the ophthalmic artery: 6 months after treatment, 26.9 +/- 7.2 cm/s, P = 0.018; 1 year after photocoagulation, 25.5 +/- 7.0 cm/s, P = 0.009; and 2 years after photocoagulation, 25.7 +/- 6.8 cm/s, P = 0.01). No statistically significant differences were found between 6 months, 1 year, and 2 years after panretinal photocoagulation. No significant correlations were found between patient age and blood velocities in diabetics and healthy volunteers.

CONCLUSIONS

Eyes with proliferative diabetic retinopathy showed lower ocular perfusion velocities than controls. Photocoagulation resulted in a reduction in ocular blood flow velocities; these values did not change during 2 years of follow-up.

[Vitrectomy in ocular complications of diabetes. I. Early and late results of vitrectomy]

Results of 168 pars plana vitrectomies (ppV) of 144 diabetics are presented. In 26.2% of eyes before surgery, vitreous hemorrhage without detachment of the retina was present. In the remaining eyes, different stages of tractional detachment occurred. Visual acuity worse than 1/50 was observed in 83.9% of eyes before surgery. Results of ppV were evaluated on the 7th day and after the 3rd, 6th, 12th and 18th month following the procedure. Anatomical and functional success was achieved in about 80% and 67% of treated eyes, respectively, over the whole follow-up period.

Early photocoagulation in patients with either type I or type II diabetes

OBJECTIVE

To determine the benefits of early photocoagulation in patients with type I versus type II diabetes.

DESIGN

One eye of each of 3,711 patients was randomly assigned to early photocoagulation; the other was assigned to deferral of photocoagulation, with follow-up visits scheduled every 4 months and photocoagulation to be carried out promptly if high-risk proliferative retinopathy developed. Patients were categorized by age and type of diabetes.

MAIN OUTCOME MEASURES

Best corrected visual acuity was measured at each study visit scheduled at 4-month intervals. Stereoscopic fundus photographs were taken and evaluated at baseline, 4 months, and yearly thereafter. Retinopathy severity was assessed from fundus photographs. Severe visual loss was defined as visual acuity of worse than 5/200 for at least two consecutive study visits.

RESULTS

Previously published results of the Early Treatment Diabetic Retinopathy Study (ETDRS) demonstrated a statistically significant benefit of early photocoagulation in preventing severe vision loss. Further analyses demonstrate that this benefit of early photocoagulation is greater in patients with type II diabetes than in those with type I. The relative benefit of early photocoagulation in patients with type II diabetes is also seen for other outcomes (development of high-risk proliferative retinopathy, development of the combined end point [severe visual loss or vitrectomy], development of moderate visual loss, or development of legal blindness). The patients most likely to benefit from early photocoagulation had severe nonproliferative retinopathy or early proliferative retinopathy. Analyses from the Diabetic Retinopathy Study confirm the relative benefit of scatter photocoagulation for type II patients. Because of the high correlation between age and type of diabetes, analyses sub-grouped by age show similar results.

CONCLUSION

These analyses suggest that patients with type II diabetes, or older patients with diabetes, are more likely to benefit from early scatter photocoagulation than patients with type I diabetes. The current standard of care is to initiate scatter photocoagulation as the severity of retinopathy approaches or reaches the high-risk stage, Provided careful follow-up is possible, ETDRS data do not show that initiating scatter photocoagulation prior to the development of high-risk proliferative diabetic retinopathy in patients with type I diabetes will reduce the risk of severe visual loss. ETDRS analyses do indicate that for patients with type II diabetes, it is especially important to consider scatter photocoagulation at the time of the development of severe nonproliferative or early proliferative retinopathy.

Reversible loss of light perception after vitreoretinal surgery

PURPOSE

We studied reversible loss of light perception after vitreoretinal surgery to show that functional vision can return in some patients.

METHODS

We reviewed the medical records of seven patients who had postoperative reversible loss of light perception in the eye that underwent vitreoretinal surgery. Differences in the postoperative courses and interventions were studied.

RESULTS

Five of the seven patients had diabetes mellitus but none had hypertension. The indications for vitreoretinal surgery were severe proliferative diabetic retinopathy in five patients and retinal detachment with advanced proliferative vitreoretinopathy in two patients. Seven patients had reversible loss of light perception within the first three postoperative days. Six of the seven patients had an intraocular pressure greater than 26 mm Hg at the time the eye had no light perception. Decreasing the intraocular pressure was associated with return of light perception in five of seven patients. Return of useful vision was gradual. Four of seven patients had a visual acuity of 20/400 or better one month after surgery, and all seven had a visual acuity of 20/400 or better three months after surgery. Visual acuity in four eyes improved further to 20/70 or better at six months or more after surgery.

CONCLUSION

Reversible loss of light perception after vitreoretinal surgery does occur in some patients. Monitoring vision and intraocular pressure is important because prompt treatment may assist in the recovery of functional vision.