9.1 INDICATIONS FOR VITRECTOMY

Vitrectomy is a specialized procedure which is the domain of

appropriately trained vitreo-retinal surgeons. Vitrectomy is used 

to achieve specific goals, which may limit or halt the progress of 

• to remove vitreous opacity (commonly vitreous haemorrhage,

also intra-ocular fibrin, or cells) and/or fibrovascular proliferation
(severe extensive proliferative retinopathy; anterior
hyaloidal fibrovascular proliferation)
.
• to allow completion of panretinal laser photocoagulation (with

the endolaser, introduced into the vitreous cavity or with the
indirect laser ophthalmoscope), or direct ciliary body laser 
photocoagulation
.
• to relieve retinal traction, tractional displacement or ectopia, 

traction detachment by removal or dissection of epiretinal 
membranes, in cases of non-rhegmatogenous retinal 
detachment
.
• to achieve retinal reattachment by closure of breaks and 

placement of internal tamponade (in cases of combined traction/
rhegmatogenous detachments)
.
• to remove the posterior hyaloid face in some cases of diffuse 

macular oedema with posterior hyaloid face thickening.

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9.2 VITREOUS / SUBHYALOID HAEMORRHAGE

Simple vitreous haemorrhage is a relative indication for vitreous 

surgery, DRS studies have shown that several factors should 

considered: the patient's age, the rapidity of progress and degree 

of severity of diabetic eye disease, the patient's appreciation of risks 

and benefits of surgery, and the patients ability to co-operate with 

surgery, and in particular with post-operative positioning, and 

supplemental laser photocoagulation where indicated. Various types 

of simple vitreous haemorrhage occurs as discussed below:

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9.2.1 Severe non-clearing vitreous haemorrhage

Vitreous haemorrhage often clears within a matter of days to weeks, 

and it is usually possible to achieve delivery of initial or supplemental 

panretinal laser photocoagulation without vitrectomy (see section on 

lasers). If laser photocoagulation is not possible, or vitreous 

haemorrhage persists for more than one month then vitrectomy should 

be considered since maculopathy and/or proliferative disease may 

progress unchecked, thus compromising the final visual result.

.

Patients with NIDDM are less likely to have severe progressive 

proliferative retinopathy and while they also gain benefit from early 

surgery, as opposed to deferred surgery (surgery deferred for more 

than 6 months) the benefit is less. These patients should nonetheless 

have surgery within 3 to 6 months from onset of persistent non-clearing 

vitreous haemorrhage.

.

Regular (2-4) weekly ultrasonic examinations are required to ensure 

early detection of retinal detachment, and clinical biomicroscopy to 

detect iris or iridocorneal angle neovascularization, or haemolytic/ghost 

cell glaucoma. Patients with any of these complications should be 

considered for early vitrectomy47-49.

a

Surgical goals and procedure

For this indication the surgical goal is to remove the vitreous

opacity through a 3-port pars plana vitrectomy procedure. The

posterior hyaloid face should be removed (this is a structural support 

for fibrovascular proliferation and its removal usually prevents 

subsequent reproliferation), and initial or supplemental panretinal laser 

photocoagulation should be performed to prevent reproliferation,

anterior hyaloidal fibrovascular proliferation, and entry site 

complications (fibrovascular ingrowth).

.

9.2.2 Non-clearing post-vitrectomy haemorrhage

Recurrence of vitreous haemorrhage is common in the early post-

vitrectomy period (2-4 weeks) but usually clears spontaneously within a

short time. In all cases where the retina cannot be adequately visualized, 

it is essential to confirm the absence of underlying retinal detachment 

with ultrasonography. If cavity haemorrhage does not clear within 2-3

weeks, revision surgery should be considered.

.

Surgical goals and procedures

The surgical goal is to remove the haemorrhage, and treat the cause. 

Revision normally requires a 3-port pars plana vitrectomy to allow an 

adequate internal search for the source of bleeding. In particular, 

examination of the previous entry sites is necessary to detect and 

treat anterior hyaloidal and/or entry site fibrovascular proliferation.

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9.2.3 Dense pre-macular haemorrhage

Subhyaloid haemorrhages may be seen with or without associated

intra-gel haemorrhage (Figure 27) these are localized to the immediate 

vicinity of neovascular complexes. Most such haemorrhages respond 

to supplemental panretinal laser photocoagulation. Dense subhyaloid 

haemorrhage occurs in the pre-macular area, in areas of localized 

posterior vitreous detachment, or in an existing premacular bursa.

Progressive fibrovascular proliferation develops in non-resolving 

pre-macular haemorrhage d involves the cortical vitreous gel with 

subsequent macular traction detachment or ectopia.

.

Indications for vitrectomy in this type of haemorrhage include severe

visual loss (for example in only eyes), failure of regression or 

resumption of haemorrhage after supplemental laser photocoagulation  

the presence of significant subhyaloid pre-macular haemorrhage in eyes 

with good pre-existing panretinal laser photocogualtion47-49.

Figure 27 Subhyaloid haemorrhage  occupying the premaulcar bursa  space.

Surgical goals and procedures

A 3-port pars plana vitrectomy is performed taking care to remove the 

posterior hyaloid face, particularly from the posterior pole and the 

temporal arcades. Haemorrhage is removed, residual membrane 

dissected and supplemental panretinal endolaser photocoagulation is 

placed if needed. Long standing cases are more likely to require 

significant membrane dissection with its attendant risk of iatrogenic 

retinal break formation.

.

Some surgeons have suggested that first-line treatment for dense pre-

macular haemorrhages is YAG laser therapy to the pre-hyaloid vitreous 

cortex, avoiding the macular area, thus releasing the trapped blood. This 

procedure is safe and may allow early visualization of diabetic 

maculopathy50-51. This is a promising procedure but is not yet standard 

practice and requires further evaluation.

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9.3 HAEMOLYTIC GHOST-CELL GLAUCOMA

Elevated intraocular pressures may be caused by vitreous haemorrhage 

specifically in those eyes with a disrupted anterior hyaloid face after 

previous vitrectomy surgery, or in aphakic eyes with vitreous haemorrhage. 

"Erythroclasts" pas from the vitreous cavity into the anterior chamber and 

obstruct the trabecular meshwork. It is important to differentiate this 

condition from steroid induced intra-ocular pressure elevation, since many 

of these patients may also be suing topical steroid drops. If the intraocular 

pressure remains elevated despite medical therapy after one to 3 weeks, 

surgery should be performed.

.

Surgical goals and procedures

Revision pars plana vitrectomy with removal of all vitreous cavity and anterior 

chamber haemorrhage is the preferred surgical procedure. Glaucoma filtering 

surgery is usually not required.

.

9.4 RETINAL DETACHMENT

9.4.1 Tractional macular ectopia and detachment

Traction retinal ectopia or detachment involving the macula is the leading 

indication for vitrectomy surgery in PDR at the present time. Tension is 

exerted on the posterior hyaloid face or cortical vitreous remnants, and 

indirectly on the retina by contraction of fibrovascular proliferative tissue 

resulting in retinal striae, macular ectopia, macular distortion and traction 

retinal detachment (Figure 28). Since the hazards of surgery are high in 

this condition, vitrectomy is generally limited to those eyes with 

a) involvement of the macula; b) evidence of a progressive extra-macular 

traction retinal detachment; c) combined traction/rhegmatogenous retinal 

detachment which threatens to involve the macula (see below). Surgery 

in cases with macular involvement for more than 6 months is usually 

associated with little or no functional improvement and is not 

recommended49,52,53.

Figure 28 Diabetic tractional detachment (arrow).

.

Surgical goals and procedures

In addition to removal of media opacity, specific goals include release of 

tractional components by removal of fibrovascular membranes, closure of 

persistently bleeding vessels and treatment of any iatrogenic retinal breaks. 

Cases with pure tractional elevation will experience spontaneous post-operative 

retinal reattachment and macular remodelling as a result of successful surgery. 

Anatomic success has been reported in between 64% to 80% of patients 

(with a 6 month follow-up) with visual function improvement in 26% 

to 65%49,52.

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9.4.2 Combined traction - rhegmatogenous retinal detachment

While most extra-macular traction retinal detachments will remain stable 

for many years even if these tissue complexes are highly elevated, in some 

patients the force of the fibrovascular traction is sufficient to create a 

retinal tear. These tears may also occur in relation to previous laser 

photocoagulation scars. These tears are frequently not identified 

pre-operatively. 

.

Clinically, a rhegmatogenous retinal detachment caused by fibrovascular 

proliferation presents with a convex configuration rather than the concave 

contour of a tractional, non-rhegmatogenous detached retina. In addition, 

white (hydration) lines in the inner retina are more characteristic of a 

rhegmatogenous component. Surgery is indicated if there is sudden visual 

loss, evidence of progressive peripheral combined traction/rhegmatogenous 

retinal detachment, or evidence of progressive iris rubeosis.

.

9.5 SEVERE WIDESPREAD FIBROVASCULAR PROLIFERATION

Some patients (typically young adult type I diabetics with a history of 

diabetes since childhood) are seen with a pattern of active fibrovascular 

proliferation that progresses despite extensive panretinal laser 

photocoagulation. These eyes have a high risk of severe visual loss and 

blindness. The Diabetic Retinopathy Vitrectomy Study Group compared 

standard laser and vitrectomy indications (with vitrectomy for vitreous 

haemorrhage, or traction macular detachment) in a randomized fashion 

with early vitrectomy surgery, in  total of 370 eyes. The number of 

patients experiencing preservation of good visual function (20/40 or better) 

was almost twice as high in the early vitrectomy group (44%) compared to 

the conventional management group (28%) after 4 years of follow-up. 

However, the proportion of eyes with severe visual loss or blindness was 

similar in both groups and this stage was reached earlier in the early 

vitrectomy group. Clinical characteristics which warrant referral for 

vitrectomy, even in the absence of extensive laser photocoagulation, 

include widespread fibrovascular proliferation (three disc diameters 

or more of fibrovascular tissue).

.

It is to be emphasized that these patients frequently have extensive 

proliferation as their sole indication and do not necessarily have vitreous 

haemorrhage or macular tractional displacement. While these patients 

should receive panretinal laser photocoagulation, the presence of high 

risk characteristics should indicate vitreo-retinal referral at an early stage.

.

Surgical goals and procedures

A 3-port pars plana vitrectomy is performed, with great ce being taken 

to remove all detectable posterior hyaloid face which is typically adherent 

to the retina.

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9.6 IRIS / ANGLE NEOVASCULARIZATION WITH VITREOUS OPACITY

Anterior segment neovascularization which is mild and non-progressive 

may be safely monitored. Progressive iris or angle neovascularization 

requires panretinal laser photocoagulation, and if vitreous haemorrhage 

prevents adequate and effective retinal laser photocoagulation, 

vitrectomy with endolaser photocoagulation is indicated. Patients with 

established neovascular glaucoma may undergo combined surgery, 

comprising pars plana vitrectomy with extensive endolaser photo-

coagulation and in some cases with additional direct ciliary body 

photocoagulation. This surgery is combined with silicone oil exchange 

in some eyes or with glaucoma filtration surgery in others. 

.

9.7 ANTERIOR HYALOIDAL FIBROVASCULAR PROLIFERATION/

RETROLENTICULAR FIBROVASCULAR PROLIFERATION

Fibrovascular proliferation on the anterior hyaloidal surface or its remnant 

is typically seen after vitrectomy in severe ischaEmic eyes of patients with 

type 1 diabetes mellitus. This fibrous tissue, which causes contraction of 

adjacent tissue and may cause peripheral traction retinal detachment, 

posterior iris displacement and lens displacement or recurrent vitreous 

haemorrhage, is highly vascular and difficulty to treat. in some patients 

this process may be localized to the area of the entry site and is 

associated with typical sentinel vessels on the adjacent episclera and 

sclera55. Anterior hyaloidal fibrovascular proliferation may also occur 

after cataract extraction in patients with active proliferative disease56.

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Surgical goals and procedure

The surgical goal is to remove all fibrovascular tissue. This requires 

basal vitrectomy, lensectomy, membrane dissection and extensive, 

confluent laser photocoagulation to the peripheral retina and pars plana, 

often combined with scleral buckling surgery and silicone oil exchange.

.