Intravenous sodium fluorescein enhances the visibility of vitreous during vitrectomy surgery for diabetic retinopathy

1 Doutor, responsável pelo Centro de Pesquisa Rubens Siqueira CPRS – São José do Rio Preto (SP), Brasil; Responsável pelo Departamento de Oftalmologia da Faculdade de Medicina de Catanduva – FAMECA – Catanduva (SP), Brasil; Colaborador em pesquisa do departamento de Retina da USP Ribeirão Preto-SP 2 Doutor, responsável pelo Departamento de Retina da Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo USP Ribeirão Preto (SP), Brasil; 3 Estagiário em Retina e Vítreo no Centro Especializado Retina e Vítreo CERV -São José do Rio Preto (SP), Brasil.


Intravenous sodium fluorescein enhances the visibility of vitreous during vitrectomy surgery for diabetic retinopathy
Fluoresceína sódica intravenosa aumenta a visibilidade do vítreo durante a cirurgia de vitrectomia para retinopatia diabética itrectomy is the treatment of choice for proliferative diabetic retinopathy with traction or persistent vitreous hemorrhage (1) .It can frequently restore useful vision in diabetic patients and reduce the risk of visual loss from traction retinal detachment (2) .
The use of dilute sterile sodium fluorescein (NaFl) has previously been suggested as an aid in vitrectomy (3-4)   .Except for two published letters (3)(4) , there are no large studies describing the safety and efficacy of intravitreal NaFl in vitreous surgery.However, there is a study that described the safety and efficacy to use Intravitreal sodium fluorescein to enhance the visibility of clear vitreous during vitreous surgery for macular hole (5)   .We will describe in this paper the efficacy of Intravenous NaFl for enhances of visibility of vitreous during vitrectomy surgery for diabetic retinopathy.

METHODS
Fourteen consecutive vitreoretinal surgery cases for vitreous hemorrhage and tractional retinal detachment, secondary to diabetic retinopathy, were submitted to intravenous sodium fluorescein 20% injection 1 hour previously the surgery (Table 1).
Surgery was performed under peribulbar anesthesia by a single surgeon (R.C.S).Standard Three-port Pars Plana Vitrectomy was performed using Accurus vitrectomy machine (Alcon, Fort Worth, Texas, USA) with the sclerotomies placed 4 mm (phakic eyes) or 3.5 mm (aphakic and pseudophakic eyes) posterior to the limbus.We do not use special filter to observe the contrast.
Limited core vitrectomy and removal of the vitreous close to the sclerotomy used for the insertion of the vitreous cutter were initially performed.In phakic eyes, in order to avoid direct trauma to the lens caused by the vitrectomy instruments, vitrectomy at the vitreous base from the 6 to 12 O'clock position was performed with the vitreous cutter held by the right hand, and from the 12 to 6 O'clock position was performed with the left hand.
Initially, the central vitreous was removed (core vitrectomy), followed by peeling of dense epiretinal membranes.Vitreous shaving was performed with scleral indentation by an assistant using a muscle hook.The images of all surgery steps were recorded.Finally, the retina was inspected by indirect ophthalmoscope and fluid-gas exchange completed the procedure.

RESULTS
The study group consisted of 14 diabetic retinopathy patients.Fluorescein stained the peripheral uncut clear vitreous green, vitreous base, posterior hyaloid and improved the visibility in all instances.
At surgery time fluorescein stained the whole vitreous (Figure 1A), especially the vitreous base and the posterior hyaloid in the posterior pole.Fluorescein also stained fibrous points (neovascularization sites) with stronger intensity making it easier these areas observation (Figure 1 D).
At vitreous base shaving, fluorescein helped in the visualization even of the retina vitreous junction, following the traction movements of the vitreous when the vitrectomy probe gets closer from the retina, and evidencing the limits of vitreous base with the periphery retina, reducing the incidence of iatrogenic periphery tears.During posterior hyaloid detachment procedure, it was possible to see the hyaloid and the adherent's areas (Figure 1 B,C).
There was no stain of the lens or capsule (pseudophakic) during surgery, and it was possible to notice that flourescein stained the anterior chamber, especially at pseudophakic patients, but did not affected the vitreous observation, not interfering at vitrectomy.No complications associated with the dye injection were observed in all cases.

DISCUSSION
The vitrectomy has shown an increase in its statement due to technical improvement mainly through better performance of equipment, speed cutting and increased less invasive systems (small gauge).One of the new tools of vitrectomy are substances capable of dyeing the structures intraocular facilitating visibility.Some dyes have been well studied as indocyanine green (ICG), trypan blue and more recently the sodium fluorescein (6)(7)(8)(9)(10) .
In order to avoid the eye toxicity and also greater manipulation during surgery (injection and aspiration of the dye), we evaluated in this study the possibility of the use of intravenous sodium fluorescein to as a dye for use in vitrectomy.
In this study we used the intravenous sodium fluorescein one hour before surgery in order to improve the visibility of areas of interest during surgery for vitrectomy in patients with diabetic retinopathy.We chose this group of patients because they show a drop of bloodretinal barrier thus facilitating the leak of f sodium fluorescein for vitreous cavity.The patients who were included in this study had diabetic retinopathy with vitreous hemorrhage (9 patients) and tractional retinal detachment (7 patients).
We observed that the sodium fluorescein stained the vitreous body, vitreous base, posterior hyaloid and sites of neovascularization.
There was no need to use any special filter for viewing the contrast.In all patients, the color green was the sodium fluorescein observed with ease and especially when put the light pipe near the area to be examined.
To remove the posterior hyaloid with active aspiration, we observe that the sodium fluorescein provided a clear vision of the posterior hyaloid moved.We also observed that the sites of neovascularization became impregnated by sodium fluorescein.This facilitated the prevention of bleeding during the removal of posterior hyaloid.
Another feature of intravenous sodium fluorescein is that there was no impregnation of the lens or the posterior capsule in pseudophakic eyes.This fact is one more advantage compared to other dye such as trypan blue that can lead to impregnation of the posterior capsule and subsequent worsening of visibility.There was greater impregnating the vitreous base compared with the central vitreous, facilitating the vitreous shaving.

Figure 1 :
Figure 1: A -View of the mid periphery showing uncut green coloured vitreous gel stained with sodium fluorescein during vitreous surgery; B,C -Posterior hyaloid detachment procedure, it was possible to see the hyaloid and the adherent's areas; D -Fluorescein stained fibrous points (neovascularization sites) with highly intensity making it easier these areas observation

Table 1 Results of the vitreoretinal surgery for vitreous hemorrhage and tractional retinal detachment secondary to diabetic retinopathy underwent intravenous injection of fluorescein to 20% 1 hour before the surgery Visual acuity is best-corrected Snellen acuity
Intravenous sodium fluorescein enhances the visibility of vitreous during vitrectomy surgery for diabetic retinopathy