Boston type I keratoprosthesis is currently an important alternative in cases of corneal blindness
for which penetrating keratoplasty does not offer a good prognosis [8
]. An important advantage of Boston K-Pro is that there is no need of systemic immunosuppression [11
]. Ma et al. has, however, recently proposed systemic immunosuppression for patients with immune mucous membrane diseases [12
]. Cases of alkali burn and multiple previous corneal grafts have a better prognosis than patients with immune mucous membrane diseases, such as SJS, Lyell syndrome and ocular cicatricial pemphigoid [7
In cases of multiples corneal transplantation, each new transplant increase the risk of graft rejection, as well as other complications, such as cystoid macular edema
and glaucoma, decreasing the median graft survival time decrease [7
]. Furthermore, in cases of severe ocular surface diseases, such as severe bilateral alkali burns and immune diseases of mucous membranes, the prognosis for corneal transplantation is poor, even with systemic immunosuppression [12
In our sample, all patients received keratoprosthesis type I. During the follow-up period, similar to other published series [6
]. Despite the high incidence of postoperative complications (85.17%), the retention rate was 85.71% in our series, during the follow-up period, consistent with previous studies [6
Currently, there are studies that indicate the validity of questionnaires to determine the quality of life in patients with visual impairment or undergoing to ophthalmological procedures, one of the most used is the VF-14 [13
]. This tool becomes valid to measure the visual function in patients with corneal disease [8
], except for patients with keratoconus
]. Also, the use of questionnaires to assess quality of life is well established in patients undergoing cataract surgery [18
]. According to Bilbao, this instrument has a high accuracy in determining the quality of life after cataract surgery, in contrast with generic scales like SF-36, which did not obtain good effectiveness in these patients [20
]. Furthermore, there are studies that use these tools to evaluate corneal transplantation patients, with an excellent response rate [8
Boisjoly et al. demonstrated a positive correlation of the VF-14 visual scale with the scale of general health SF-36 in patients undergoing corneal transplantation [15
]. Recently, Cortina and Hallak show the impact of Boston keratoprosthesis (KPro) implantation on patient using the National Eye Institute Visual Function
Questionnaire 25 (NEI VFQ-25) [21
]. The quality of life of these patients significantly improved postoperatively compared with their preoperative status [21
In our sample, we decided to use the VF-14 and SF-36 questionnaires because they are already well established in the assessment of quality of life in patients with visual disability [15
]. It is known that the improvement of corneal transparency
is not synonymous with functional improvement in these patients. In some cases, a good visual acuity after the procedure is not correlated with a better quality of life. In our series of cases there was, however, a strong positive correlation between the results of postoperative VA with the VF-14. Patients with better postoperative VA had better results in the VF-14 responses, with a statistically significant difference between groups. When the SF-36 results were analyzed, which is an index of perception of general health, we found, however, a statistically significant correlation with VA only in only three of the eight domains, for the whole sample.
When we correlated both the questionnaires, we observed a positive correlation with the VF-14 in five of the eight domains of SF-36, when analyzed for the entire sample. When we separated the analysis for VA, in the group of best vision, the five domains remained with a positive association; in the lowest VA group only one domain had a positive correlation (mental health).
Although the general health questionnaires such as the SF-36 did not show a good discriminative ability to measure the functional outcome of ocular interventions, in our sample there was a good correlation with the SF-36 in patients that had a good postoperative VA in comparison to the VF-14. Thus, beyond the specific questionnaires for visual function, in some cases, the general health questionnaires can be availed for a more comprehensive analysis of general patient health.
The main limitation of this study arises from methodological concerns regarding a ‘‘before and after’’. For a strong conclusion, a cohort study delineation would be more appropriated, comparing scores before and after surgery
, as Cortina and Hallek’s paper.[21
] However, this was not possible because our first surgeries were ten years ago and questionnaires were not applied in that time. Because of that, we decide to divide our patients in two groups based on visual acuity
and to compare score results of both groups - a cross sectional study. In despite of, our interpretation is that the observed differences were clinically important.
In conclusion, we observed that in our sample Boston KPro implantation has the potential of significantly improving the vision-related quality
of life in patients with poor prognosis. Patients who achieve a better visual acuity have better measures on quality of life scales, as compared to those with worse visual outcomes.