Diode laser, vitrectomy and intravitreal triamcinolone. A comparative study for the treatment of diffuse non tractional diabetic macular edema

PURPOSE

To determine the effectiveness and safety of diode laser, pars plana vitrectomy (PPV) with gas tamponade, and intravitreal triamcinolone (IVT) as possible treatments for diffuse diabetic macular edema (dDME). To determine whether the new macular edema Classification previously proposed by some of the authors may help as a guide in the choice of treatment.

METHODS

A retrospective, comparative study of 169 eyes with dDME that underwent treatment. The eyes divided into 3 groups: in the PPV Group, 59 eyes received PPV with gas tamponade; in the DIODE Group, 53 eyes received a laser grid; in the IVT Group, 57 eyes received an intravitreal injection of 4 mg of triamcinolone acetonide. The follow up ranged from 6 to 24 months. The eyes were classified according to the new DME Classification based on OCT.

MAIN OUTCOMES

Change in foveal thickness as determined by Optical Coherence Tomography (OCT); change in visual acuity; intra and postoperative complications.

RESULTS

Mean visual acuity (VA) improved at 3 months with every treatment. At one year only eyes which underwent PPV still had better VA than the pre-op value, while eyes which underwent IVT and laser treatment showed regression. PPV show the greater percentage of eyes which gain 3 or more lines of VA at one year (17%). Mean foveal thickness improved at 3 months with every treatment. Only the eyes into the PPV Group showed relatively low foveal thickness at one year. Better final VA and foveal thickness were obtained if preop VA is > or = 0.3 and if earlier stages of DME were treated according to the new DME Classification. PPV was the treatment which offered the most stable results with at one year or longer. Similar results were observed into the PPV Groups as a whole and into a subgroup of eyes with preoperative PVD. No complications were encountered with laser diode treatment. Long term complications into the IVT Group were elevated IOP (8%), retinal detachment (3.5%) and posterior cataract (15%). Long term complications into the PPV Group were retinal detachment (3.4%) and cataract (90%).

CONCLUSIONS

Diode laser, PPV with gas tamponade and IVT are effective alternative treatments to decrease foveal thickness and improve visual acuity in eyes with DME. However while the results of PPV are stable in the long term follow-up, diode laser and IVT do not offer stable results. Complications may be severe with PPV and IVT. It is necessary to carefully select cases which would benefit from these types of treatments. The authors think that the OCT Classification may serve as a guide for the choice of treatment.

OCT in the monitoring of visual recovery after uneventful retinal detachment surgery

The aim is to describe 5 cases of unexplained visual impairment after uneventful episcleral surgery associated with submacular lesions occurring post-operatively (bleb-like syndrome). The 5 cases were followed with biomicroscopy and OCT for up to 6 months. At biomicroscopy the 5 eyes presented no visible abnormalities or a yellow subfoveal dot. OCT demonstrated the presence of isolated or multiple subfoveal or submacular blebs. Some cases experienced partial or total slow spontaneous resolution, while other blebs remained stable for months or slightly enlarged. In conclusion, OCT can play an important role in the follow up of patients with unexplained visual impairment after episcleral surgery and diagnose the presence of small subfoveal shallow retinal detachments persistent for months after surgery. We think that OCT should be routinely considered in the follow-up of these patients.

Diabetic macular edema: an OCT-based classification

PURPOSE

More than ten years after ETDRS, Optical Coherence Tomography (OCT) greatly enhanced our ability to detect macular thickening and has brought new insights on the morphology of edema and on the presence of vitreal traction. In this study we propose a new classification of macular edema based on OCT findings to better catalogue and follow this complex clinical entity.

METHODS

Since January 2000 we analysed with OCT 2 (Zeiss Inc.) more than one thousand and two hundred eyes with DME.

RESULTS

The classification takes into account five parameters: retinal thickness, diffusion, volume, morphology and presence of vitreous traction. Standard figures and numerical values for every parameter are given.

CONCLUSION

Although ETDRS guidelines for laser treatment of DME still remain the only proven therapy for this condition, many other strategies are now on trial, and the vast majority of authors use OCT as the best indicator of therapeutic benefit. The amount of information given by OCT demonstrates that macular edema is a complex clinical entity with various morphology and gravity, and disclaimed the limitations of a simple "clinical" definition. As in many other examples such as macular holes and choroidal neovascularization, a uniform and precise definition of macular edema would increase the possibility to compare and judge the result of different therapeutic strategies. Aim of this classification is to implement the ETDRS clinical definition of DME with the precise and useful data given by OCT to better diagnose, catalogue and follow macular edema.

Cataracts associated with posterior segment surgery

Although cataract is widely described among the complications of vitrectomy, the precise relationship between vitrectomy and the development of lens opacity is not completely understood. This article presents an extensive literature review and the authors' personal experience with this complication.

Role of OCT in the diagnosis and follow up of diabetic macular edema

The aim is to present, along with a brief literature review, the results of OCT scan in eyes with diabetic macular edema (DME), as well as examples of the utility of OCT for different therapeutic approaches. One-hundred and thirty-six eyes with diabetic retinopathy were analyzed with OCT to explore the different patterns of DME. Some eyes with DME were studied with OCT pre and postoperatively to determine the efficacy of photocoagulation and vitrectomy to restore a normal macular profile. Sixty-eight eyes with a central foveal thickness of 200 mu or more were considered "edematous". Three different patterns of DME were recognized and analyzed: macular thickening, cystoid macular edema and shallow retinal detachment. The change in macular profile and internal retinal structure after laser or surgical treatment are well visible with OCT. OCT contributes in understanding the anatomy of DME and the intraretinal damage and seems to be the technique of choice for the follow-up of macular edema. We think that this tool should always be used in monitoring the effect of therapies in future studies.

Relationships between vitreoretinal and refractive surgery

OBJECTIVE

To describe retinal complications after posterior chamber phakic intraocular lens (PCPIOL) implantation and refractive surgery complications after scleral buckling surgery.

DESIGN

Retrospective, noncomparative, small case series.

PARTICIPANTS

Four patients in whom retinal detachment developed after PCPIOL implantation and two patients with previously placed encircling scleral buckles in whom corneal steepening developed after laser in situ keratomileusis (LASIK).

INTERVENTION

The four patients with retinal detachment after PCPIOL implantation underwent vitreoretinal surgery. One of the two patients in whom corneal steepening developed after LASIK underwent buckle removal.

MAIN OUTCOME MEASURES

The main parameters evaluated were vitreoretinal findings, corneal topography, and pachymetry.

RESULTS

Retinal attachment was achieved for all patients. Mean postoperative best-corrected visual acuity (BCVA) was 20/30. One patient lost one line of BCVA. One patient with corneal steepening achieved partial corneal flattening after buckle removal.

CONCLUSIONS

Vitreous base stimulation related to PCPIOL implantation and manipulation during LASIK may trigger retinal complications. Laser in situ keratomileusis in patients with previously placed scleral buckles may result in unexpected corneal steepening.

Central Necrotic Lamellar Inflammation After Laser in situ Keratomileusis

PURPOSE

To report four cases of corneal interface complications that occurred after excimer laser in situ keratomileusis (LASIK).

METHODS

Four eyes of three patients underwent technically uneventful LASIK.

RESULTS

One day after LASIK, patients presented with severe pain, blurred vision, conjunctival infection, and diffuse opacity at the interface. Two days after LASIK, significant features were central opacity, striae in the flap, loss of uncorrected and best spectacle-corrected visual acuity, and corneal sensitivity. The findings did not improve by using drugs or by lifting the flap and irrigating the bed. The central opacity partially resolved over 8 to 12 months, leaving a hyperopic shift (one patient), striae (one patient), and loss of two or more lines of best spectacle-corrected visual acuity (three patients).

CONCLUSION

This severe central inflammation after LASIK could be an extreme manifestation of diffuse lamellar keratitis.

Visual acuity disturbances in chronic renal failure

Patients affected by chronic renal failure often complain of blurred vision when submitted to hemodialysis. Refraction, visual acuity and lens transparency have been evaluated in 36 eyes of 18 patients who underwent hemodialysis, before and after the treatment. Student's t test did not prove any statistically significant difference between the considered parameters. However, a change in refraction was noted in 64% of the eyes, always in hyperopic mean. Corrective glasses had to be changed to ensure the same visual acuity as before the hemodialytic treatment. Particular care must be taken in lens prescription in those patients who could undergo dialysis for chronic renal failure.

Epidemiology of endogenous uveitis in north-eastern Italy. Analysis of 655 new cases

PURPOSE

To report the results of a retrospective analysis among endogenous uveitis patients in the north-eastern area of Italy.

METHODS

The authors reviewed a series of 655 new cases treated between October 1986 and December 1993. The incidence of endogenous uveitis was calculated based on a 100,000 patient population.

RESULTS

The average incidence was 11.40/100,000. The majority of patients were between the ages of 20 and 70 years (74.43%). A probable diagnosis was determined in 55.57% of cases; anterior uveitis was diagnosed in 58.01% of cases, posterior uveitis in 26.11%, panuveitis in 12.98%, and intermediate uveitis in 2.9% of cases. The authors observed recurrences in 25.49% of cases. While the first cases are almost equally distributed in the various months, the recurrences seem to be significantly more frequent in the cold (from November to February; mean air temperature <8 degrees) and transitional months (October and from March to May; mean air temperature from 8 degrees C to 18 degrees C) than in the warm months (from June to September; mean air temperature >18 degrees C). Respectively p=0.003 and p=0.029.

CONCLUSION

The incidence in this series is lower than in other European and American studies. Despite the high rate of idiopathic cases in this study, the authors support that the presentation of single case experiences may allow improved multi-centric analysis and a greater understanding of the epidemiology of uveitis.

Choroidal calcification in Bartter syndrome

PURPOSE

Bartter syndrome is characterized by hyperplasia of the renal juxtaglomerular apparatus, hyperaldosteronism, and hypokalemic alkalosis. We report a case of Bartter syndrome associated with normal serum calcium levels and posterior choroidal calcification.

METHODS

Case report. A 59-year-old man with bilateral cataract and Bartter syndrome underwent a complete ophthalmic examination, including standardized echography before and after cataract surgery.

RESULTS

Before cataract surgery, echography identified small, hyperreflective, multifocal, bilateral choroidal lesions with posterior shadowing. After surgery, these lesions appeared as yellow-white, barely elevated plaques with smooth edges and were diagnosed as choroidal calcification.

CONCLUSIONS

Choroidal calcification may occur in patients with Bartter syndrome. This condition should be added to the differential diagnosis of posterior segment calcification.

Hydroepithelial Keratectomy in Rabbits with a Waterjet-based Instrument

BACKGROUND

Corneal epithelial removal finds multiple applications in ophthalmic surgery (epithelial herpes infections, recurrent epithelial erosion, corneal ulcers and plaques, and intraoperative epithelial clouding). Photorefractive keratectomy is initiated by removal of the epithelium. Current techniques for epithelial removal are suboptimal. We studied the safety and effectiveness of a new technique, hydroepithelial keratectomy, performed with the HydroBrush keratome on live rabbits.

METHODS

Eighteen rabbits (18 eyes) underwent hydroepithelial keratectomy and 18 rabbits (18 eyes) underwent epithelial removal with a surgical blade (blade group). Twelve rabbits were euthanized immediately after the procedure. Twenty-four rabbits were followed for up to 120 hours after treatment. Ultrastructural analysis was performed with light and electron microscopy.

RESULTS

The hydroepithelial keratectomy group healed a mean 53 hours after treatment; the blade group healed a mean 78 hours after treatment. The HydroBrush keratome exposed the basement membrane and the basal cell membrane of the epithelium. The blade exposed patches of basement membrane, as well as stroma and cell debris.

CONCLUSIONS

Hydroepithelial keratectomy with the HydroBrush keratome is effective and safe. Wound healing after hydroepithelial keratectomy is faster than after blade removal. Unlike the blade, the HydroBrush keratome exposed a smooth surface, devoid of debris, with well-defined edges and round shape without hydration nor dehydration of the tissue.

Principles and Microscopic Confirmation of Surface Quality of Two New Waterjet-based Microkeratomes

PURPOSE

The HydroBlade and the HydroBrush keratomes are waterjet-based devices for corneal surgery that operate at normal intraocular pressure in two different modes: removal of parallel or shaped lenticules or hinged flaps with a small diameter, high speed waterjet; and removal of the epithelium with a waterjet sheet. The operating principles as well as histology of the cut surfaces are described.

METHODS

A flap was made in one cadaver eye with a Chiron ACS keratome and in the second eye with the HydroBlade keratome. The epithelium was removed in one cadaver eye with a surgical blade and in the second eye by the HydroBrush keratome. Scanning and transmission electron microscopy and light microscopy was obtained.

RESULTS

The HydroBlade keratome cleaved only cross-linking fibrils and left intact keratocytes. Shape and dimensions of the flap were accurate. There was no observable hydration or significant heating of the tissue. Mechanical forces on the cornea were small. The HydroBrush keratome removed the epithelium quickly, left no epithelial debris, and did not damage Bowman's layer.

CONCLUSION

With the HydroBlade keratome, the cuts are ideal blunt dissections. Epithelial removal with the HydroBrush keratome is effective and quick.

In vitro transplantation of fetal human retinal pigment epithelial cells onto human cadaver Bruch's membrane

Retinal pigment epithelium transplantation has been proposed as adjunctive treatment for age-related macular degeneration following surgical excision of choroidal neovascular membranes. The goal of this study was to develop a model to evaluate retinal pigment epithelium transplantation onto human Bruch's membrane in vitro. We investigated the ability of cultured fetal human retinal pigment epithelium to colonize human cadaver Bruch's membrane, determined the incubation time needed to form a monolayer and to exhibit apical microvilli and tight junctions, and assessed the production of basement membrane. Freshly enucleated (less than 48 hours old) human eyes were cut through the pars plana, and the anterior segment, vitreous, and retina were removed. The native retinal pigment epithelium was debrided with a surgical sponge. Bruch's membrane and choroid at the macula were trephined with a 7.0 mm diameter trephine and then incubated with 1/2 ml of Dulbecco's modified Eagle's medium +15% fetal calf serum+basic fibroblast growth factor (1 ng ml-1), and fetal human retinal pigment epithelium at a concentration of 242,000 cells ml-1. Specimens were incubated for 1, 4, 6, 8, 12, or 24 hours. The specimens were fixed in half strength Karnovsky's fixative, processed, and analysed with scanning and transmission electron microscopy. The retinal pigment epithelium covered the debrided macular specimens to different degrees at different incubation times. After 1 hour, the cells started to attach and flatten (median percent coverage: 78%). The extent of Bruch's membrane coverage by fetal retinal pigment epithelium varied greatly between specimens. After 4-6 hours, the cells covered the entire debrided surface in a monolayer (median percent coverage: 97.2% at 4 hours, 99.8% at 6 hours). Tight junctions were observed, and the cells had few apical microvilli. The lateral cell borders were obliquely oriented with respect to Bruch's membrane, and the nuclei were elongated, exhibited prominent nucleoli, and were oriented parallel to Bruch's membrane. After 6-8 hours, cells started to become hexagonal (median percent coverage at 8 hours: 99.97%). Cells attached to the inner collagenous layer tended to be flatter than cells attached to residual native basement membrane. At 12 and 24 hours, expression of hexagonal shape, tight junctions, and apical microvilli were observed more frequently (median percent coverage: 99.87% at 12 and 100% at 24 hours). No newly formed basement membrane was observed at these time points. In separate experiments comparing attachment in the presence and absence of native RPE basement membrane, the presence of native retinal pigment epithelial basement membrane promoted the early attachment of the cells and more rapid expression of normal morphology. This in vitro system provides a reproducible way to study the adherence of retinal pigment epithelium to normal and diseased human Bruch's membrane.

[Do radiologists develop perceptual learning contrast sensitivity?]

A slight difference in brightness between objects close to each other and with no clear-cut outlines separating them can be recognized by the visual function called contrast sensitivity. This function is particularly developed in the radiologist, whose task is to analyze images in many shades of grey and with no clear-cut outlines, due to kinetic and radiogeometrical shading. Assuming that professional habit might develop this function, the authors compared contrast sensitivity in a group of 26 radiologists with contrast sensitivity in a control group (30 non-radiologists). The Vistech VTCS 6500 test was chosen for the task because of its practicality and reliability. The test consists in the recognition of the orientation of 5 series of alternate bright and dark lines differencing in thickness and contrast. The results obtained in the two groups were studied and compared with the statistical test of the analysis of variance, the T-test by Student and the U-test by Mann-Whitney. Contrast sensitivity was surprisingly higher in the radiologists group, in 4 of 5 series of images with bright and dark lines, than in controls and the difference was statistically significant: p < 0.001 with the test and the U-test. A deviation standard increase in contrast sensitivity was found also in radiologists with short-term professional activity (a few years). To explain these results, two hypotheses one suggested by the authors: radiologists pay greater attention to image details, because of their profession; perceptual learning--that is an improvement in the image-research cortical function--might occur, because of constant training. In the radiologist to conclude repeated stimulation of research capabilities in low-contrast images is thought to improve the efficiency of this cortical function.