Pars plana vitrectomy (PPV) procedure is a closed-system intraocular operation. It
is considered to be an eminent step in the evolution of vitreoretinal surgery. It
was introduced in 1971 by Norton and Machemer. Since then, PPV had advanced tremendously
in various aspects, especially in port's size and cut rate. Smaller gauge PPV (25G
and 27G) is currently used to treat various vitreoretinal conditions.
PPV is indicated to treat different vitreoretinal conditions such as retinal detachment,
dropped crystalline lens materials, vitreous hemorrhage, and endophthalmitis. However,
vitreoretinal conditions are often present with simultaneous cataract. On the other
hand, PPV is a procedure which is dependent on detailed visualization of the surgical
field and depth of focus, and therefore, the clarity of the ocular media is an essential
requirement for complete and successful vitreoretinal surgery. Hence, combined PPV
with cataract extraction is a widely accepted approach. In fact, the recent technical
advances in instrumentations and small incision approach for both cataract surgery
and vitrectomy make it easier to combine both surgeries.
Cataract surgery, when it is combined with PPV, includes either phacoemulsification
or extracapsular cataract extraction. During the combined procedure, the cataract
surgery is usually performed before PPV. The decision for combined approach is easy
when the cataract is visually significant. Hence, this will be an advantage to both,
the patient and the surgeon. The dilemma comes up when the cataract is mild or even
nonexistent. Some surgeons will proceed with PPV only, and the cataract extraction
is left for another sequential surgery if needed. Others will still go ahead with
the combined surgery.
Preservation of the crystalline lens when performing PPV has some benefits. This is
true especially in pediatric population when accommodation function of the crystalline
lens is crucial in this age group. The accommodation is very crucial during the visual
development of a child. It also provides an important aid to perform daily activities
in older children. Incidence of post-PPV cataract in children is not low since cataract
can develop in 15% of pediatric eyes after PPV. On the other hand, lensectomy during
PPV is sometimes important in selected pediatric group such in eyes with concomitant
cataract and/or ectopic lenses. In some cases, in which manipulation of peripheral
retina is required, lens extraction is a preferred tactic to provide more space and
avoid the risk of lens touch during PPV.
Performing PPV alone in phakic older age patients is a gray zone. Decision for lens
extraction should be revived by the operating surgeons before proceeding to PPV. It
is also a challenge to some vitreoretinal surgeons who are not expert in cataract
surgeries. Lens accommodation, as mentioned earlier, is lost when the lens is extracted,
and that is more obvious in younger patients, who are less than 40 years of age. Some
anterior segment adverse events such as corneal decompensation and inflammatory reaction
are also more possible to occur after the combined surgery, but usually, they are
Flipping the coin to the other side will open the discussion further. Certainly, multiple
surgeries on the same eye add an extra stress for that eye. Combined surgery of cataract
extraction and PPV has many advantages over PPV alone on phakic eyes. These advantages
are clinical, economical, and even social. A vitreoretinal surgeon certainly finds
it easy to perform PPV when an eye is either pseudophakic or aphakic. PPV in phakic
eye carries the risk of lens touch, which might occur in 4%–9% of cases.[3
4] Lens touch is possible, especially when peripheral retina is approached by vitrectomy
instruments during PPV. Examples of such situations are peripheral retinal breaks
and presence of anterior proliferative vitreoretinopathy (PVR). In these circumstances,
the surgeon needs more space to reach the pathological areas in order to perform the
required actions. Furthermore, PPV alone in phakic eye will result in the development
and progression of cataract in that eye soon or later. This will necessitate the removal
of the cataract by another surgery. This, of course, will add more cost in long term
because two separate operations are more costly than a single combined surgery.
Moreover, the rate of posterior capsule rupture during the cataract extraction is
higher in vitrectomized eyes. Further to that, patients, who undergo two separate
surgeries, are exposed twice for the risk to develop intraoperative and postoperative
complications such as endophthalmitis, retinal detachment, and suprachoroidal hemorrhage.
The risk of those complications is only once if the combined approach is chosen. Prediction
of refractive status postcombined surgery is not considered as an issue since an accurate
biometry calculation is done with very sensitive and precise equipment taking in consideration
a mild myopic shift from PPV itself. Furthermore, vitrectomized eyes are anatomically
different as the anterior chamber gets deeper with fluctuation and the zonules are
weaker, and therefore, cataract surgery becomes more challenging. Interestingly, the
development of posterior capsular opacity is less common after combined procedures
in comparison to sequential surgery, 12.5% versus 24.2%. Similarly, the development
of iris rubeosis was found to occur less frequent after a combined procedure than
after PPV alone, 2% versus 15%.[9
10] In some patients, silicone oil is used as an intraocular tamponade during PPV,
so if cataract surgery is planned for patients with oil-filled eyes, then it is not
easy to get accurate biometry calculation and the surgery itself is technically difficult.
In addition, some patients, who have a phobia from surgeries, prefer to have the combined
procedure instead of exposing themselves twice for such procedures.
As a conclusion, both decisions of combined or sequential surgery have pros and cons.
However, for long-term benefits, combined surgery seems to have a better outcome with
less disadvantages. Furthermore, if decided to do PPV on phakic eyes without lens
extraction, it is always useful to have a biometry calculation of the intraocular
lens preoperatively. This will improve the surgical outcome if a decision of lens
removal is taken intraoperatively for unexpected reasons.
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Conflicts of interest
There are no conflicts of interest.