|Year : 1987 | Volume
| Issue : 3 | Page : 129-131
Magnetic intra ocular foreign bodies in the posterior segment
Call Ophthalmic Institute, Little Flower Hospital, Angamally-683 572, India
T P Ittyerah
Call Ophthalmic Institute, Little Flower Hospital, Angamally-683 572
Source of Support: None, Conflict of Interest: None
Twelve cases of magnetic intra ocular foreign bodies in the posterior segment extracted through the pars plana during 1984 to 1985 have been analysed in detail. Besides removal of the intra ocular foreign bodies, some cases required multiple procedures like lensectomy, vitrectomy and laser photocoagulation to regain and retain useful vision. Of the 12 patients 8 regained good and useful vision.
|How to cite this article:|
Ittyerah T P. Magnetic intra ocular foreign bodies in the posterior segment. Indian J Ophthalmol 1987;35:129-31
| Introduction|| |
The retention of a foreign body within the eye is a frequent event during ocular trauma due to rapid industrialisation. Magnetic foreign bodies are more common during industrial injuries because iron and it's alloys are the metals frequently used.  Out of the 94 infra ocular foreign bodies reported by Dhir S. P. et al  in 1984, 75 were magnetic. The presence of a foreign particle within the globe is a serious matter in ocular injury due to several factors viz: mechanical damage caused at the time of accident immediate infection and subsequent development of siderosis bulbi and sympathetic ophthalmia. From the clinical point of view the magnetizability of the particle is very important Magnetic foreign bodies have a comparatively better prognosis than non-magnetic ones as they can be removed more readily and with less trauma using magnets. 
| Materials and Methods|| |
This report deals with a study on twelve patients with magnetic intra ocular posterior segment foreign bodies who were admitted in our hospital in the year 1984 to 1985. The mode of injury was noted and detailed ocular examination was done in all cases The wound of entry of the foreign body and damage to various ocular structures also recorded.
| Method of localization|| |
The limbal ring method was employed to localize the foreign bodies and radiographs were taken (a postero-anterior view and lateral views with the eyes looking up, down and straight). The foreign body was then located with reference to a schematic eye drawn on the gray film (lateral view). 
| Method of extraction|| |
The foreign particles were extracted through the pars plana route using a giant magnet A preplaced mattress suture was applied and the tip of the magnet was placed at the site of the incision. The magnet was then switched on & off repeatedly till the foreign body hit the tip of the magnet The incision was closed with the pre-placed suture and the tenon and conjunctiva were sutured over it
| Observations|| |
Analysis of the twelve cases in our hospital showed that the use of hammer and chisel was responsible for the intra ocular foreign body in all except one (in the below 10 age group), when the injury occurred while observing people at work All the patients were males and majority were adult males of the working age.
Nine of the twelve patients (75%) were in the 2nd to 4th decade. There was no predilection for either eye The time interval between infliction of injury and reporting at the hospital ranged from a few days to five years Five patients (41.67%) presented within a few days and 3 (25%) within 2 weeks Four patients (33.33%) reported late, (the duration of trauma ranging from 2 months to 5 years)
The wound of entry of the foreign body was corneal in 5 eyes (41.67%) and limbal in 7 eyes (58.33%). The location of the foreign particles within the eye was in the posterior segment in all cases, as they were all flying metallic particles hitting the eyes with great velocity and therefore having sufficient energy to pierce the ocular coats and pass to the posterior segment In 10 eyes (83.33%) the intra ocular foreign bodies were located in the vitreous and in 2 eyes (16.67%) in the retina Complications like siderosis were found in 2 cases (16.67%) with long standing injury, one of which was six months old and the other 5 years Retinal detachment was seen in 2 patients (16.67%) of which one was an exudative detachment The lens was injured in 8 eyes (66.67%) and 7 patients (58.33%) had vitreous haemorrhage. Four of the twelve eyes (33.33%) developed frank intra ocular infection
Removal of all the metallic foreign bodies was done through the pars plana with a giant magnet Two eyes with corneal tear required wound repair with abscission of prolapsed uveal tissue Apart from extraction of the foreign bodies other additional procedures were also done For cataract, lensectomy was performed in 7 out of 8 cases In a forty two year old man cataract extraction was done later. Parsplana vitrectomy was done in 8 patients Indications for vitrectomy were vitreous haze, vitreous haemorrhage and strong fibrous adhesions of the intra ocular foreign body to the retina and vitreous Of the 2 patients with the magnetic foreign body located in the retina, one presented with a retinal detachment and underwent detachment surgery and in the other a local plomb was applied at the site of the retinal tear after cryopexy. In one case, a retinal hole occurred as a late complication at the macula away from the fovea and it was sealed by LASER photocoagulation
The final visual outcome depended to a great extent on the duration of injury and also on the development of serious complications Of the 8 cases which presented within two weeks after trauma, in 6 patients after surgical intervention the improvement in vision was good being in the range of 6/9 to 6/18. Two patients developed intractable infection after trauma and therefore inspite of medical and surgical measures did not regain useful vision In the 4 cases of longstanding injury, 2 patients who reported within a few months regained fairly good vision (6/24), while in 2 others their visual acuity was only light perception and 3/60.
| Discussion|| |
Perforating injuries of the globe with retained intra ocular posterior segment foreign bodies most frequently result from occupational activities and hence predominantly involve males in the working age group. The use of hammer and chisel was the cause in our patients In all cases the metallic foreign bodies were magnetic The ultimate prognosis was therefore better than when compared to non-magnetic particles as they could be easily extracted with the help of a magnetic. However with regard to non-magnetic foreign bodies and impacted magnetic foreign bodies which behave like non-magnetic ones, the prognosis is not as gloomy as it was previously. This is because of the advances made in endo procedures
Extraction of all the foreign bodies was done through the parsplana using a giant magnet The parsplana route was preferred, to an incision made directly over the site of lodgment of the foreign particle as in some cases the site was found to be too posterior after localization and therefore difficult to approach. Besides, extraction by the direct approach involves making a tear in the retina which would require an additional buckling procedure. Yet another advantage of the parsplana approach is that other operative procedures like vitrectomy and lensectomy could be done through the same incision. However, extraction of intra ocular foreign bodies through the parsplana route has it's own disadvantage. The foreign body is thought to be dragged over the retina in some eyes. But in the cases done at our hospital problems due to dragging of the foreign body over the retina were not encountered. This was probably because the magnetic pull was in a straight line and thus avoided the retina which is curved
| Conclusion|| |
It is evident from the above analysis that with the introduction of recent advanced techniques in ophthalmology (like lensectomy, vitrectomy and laser photocoagulation) the chances of regaining useful vision following retained magnetic intra ocular foreign body are no longer bleak This is true provided the patients present for treatment immediately after injury and they do not develop intractable infection.
| References|| |
Ittyerah T.P. (1978) Journal of the Kerala State Ophthalmological Society 4 : 29.
Dhir, SP. et al (1984) Ind J. Ophthal 32: 289.
Duke Elder, S (1972) System of Ophthalmology VoL XIV Part I; Henry Kimpton London, P. 169.
Stallard, I-La (1980) Stallard's Eye Surgery, John Wright & Sons Bristol, P. 778.
[Figure - 1], [Figure - 2]