14.7.5 PPV: The Anterior Segment

Deal with any problems with the anterior segment Þrst.

14.7.5.1 The Lens

Small capsular tears may self-seal with only the development of localised cataract so that some crystalline lenses can be preserved (Pieramici et al. 1996b). Phacoemulsify the lens if it is going cataractous, but be aware there may be damage to the anterior or posterior capsules or to the zonular Þbres (Tyagi et al. 1998). The patients are usually young, and therefore the lens is often soft, requiring only phaco-assisted aspiration. Dropping the lens into the vitreous is not a high risk because the lens is soft. In any case, if some dislocates, this can be dealt with during the PPV. If the IOFB is large and the intention is to remove it through the anterior chamber, delay the IOL implantation until the end of the operation. If the capsular damage is severe and the nucleus hard, use an extracapsular approach with an irrigating loop to support the lens during removal to avoid dislocating the whole nucleus into the posterior chamber. Try to preserve capsule to allow support for the IOL. Alternatively, remove the nucleus by fragmatome from the posterior approach, but maintain anterior capsule for a sulcus Þxated IOL.

14.7.6 PPV: The Posterior Segment

Perform the PPV and clear the vitreous away from the IOFB so that it is loosened and so as not to incarcerate vitreous into the forceps during extraction. If the IOFB is small enough, remove it through a sclerotomy. Judge the size of the IOFB in cross-section remembering that a square end requires an even larger slit for removal. Add the size of the forceps tips (most are larger than 20 gauge) into the estimation of the size of sclerotomy. Enlarge the sclerotomy, which is furthest from the IOFB. By using this sclerotomy, the IOFB can be removed in a perpendicular fashion from the retina whilst avoiding any scraping the retina or choroid. Insert diamond-dusted IOFB forceps through this sclerotomy. Grasp the free end of the IOFB. Take care that you do not grab either retina or vitreous; if you do, disengage and clear more vitreous from the IOFB, or using one leg of the forceps, tip the IOFB gently away from the retina and try again.

Bring the IOFB into the vitreous cavity, and without releasing the forceps draw it to the sclerotomy and remove through the sclerotomy. Sew over this sclerotomy to leave the usual 20-gauge aperture for the rest of the operation. You will most likely have to induce a posterior vitreous detachment and then remove the remaining vitreous. Removing the posterior hyaloid will reduce the chance of tractional bands causing later tractional retinal detachment.

Inspect the impact site.

A number of situations arise:

1. Local whitening of the retina without tear. Take no action and close up.

2. Tear to the retina. Apply laser around the tear and Þll the eye with the appropriate gas.

3. Tear to the retina and choroid. Laser the retina and insert silicone oil.

4. Tear to the retina and choroid and perforation of the sclera, that is, a perforating injury. Prognosis is poor. Laser around the impact site and insert silicone oil if possible.

Publications describing patients who have not received retinopexy or PVD peel during surgery, but these procedures now have low morbidity, and their avoidance is not recommended (Ambler and Meyers 1991).

Occasionally, the IOFB is so large that to remove it through a sclerotomy would require a wound so big that it would destabilise the globe during the operation. A large IOFB usually injures the lens often with pre-existing disruption of the integrity of the capsule. Therefore, a cataract extraction has been necessary. This provides the surgeon with two features which are useful:

1.A pre-existing wound used for the cataract extraction

2.Access to the anterior chamber from the posterior chamber In this circumstance, Þll the anterior chamber with vis-

coelastic. Grasp the IOFB with the forceps and pass the IOFB through the pupil into the anterior chamber. With the free hand, cut the sutures, open the cataract wound, insert forceps into the anterior chamber, take hold of the IOFB and remove it through the wound.

Fig. 14.90 An air-gun pellet has been removed via a corneal section. This pellet was lodged at 6 oÕclock, damaging the lens and the posterior segment

Fig. 14.95 See Fig. 14.92

IOFBs tend to demonstrate a less severe outcome than other severe ocular trauma with only 27 % retaining 20/200 or worse vision and 50 % attaining 20/40 vision or better (Wani et al. 2003). The visual outcome is worse when there is retinal detachment, a large IOFB or additional anterior segment injury (Jonas et al. 2000).

Fig. 14.97 Two months later, the changes in the RPE are more extensive from siderosis