Intra-operative assessment of toric intra-ocular lens implantation

angle formed by the marked 0–180 axis and the toric IOL axis after implantation with the use of the appropriate software. If IOL implantation was assessed to be inaccurate, the surgeon was advised to correct IOL positioning by rotating the IOL clockwise. The assessment procedure was repeated until accurate IOL positioning was achieved. A 14-year-old girl presenting with visual loss in both eyes was diagnosed to have healed toxoplasma retinochoroiditis in the right eye with active choroidal neovascularization (CNV) secondary to toxoplasmosis in the left. She underwent combination photodynamic therapy (PDT) and intravitreal bevacizumab as primary treatment. PDT was performed as per the ‘Treatment of Age-related Macular Degeneration by Photodynamic therapy’ study protocol and was followed by intravitreal bevacizumab after 2 days. CNV regressed at 8 weeks of follow-up and remained stable at 8 months of follow-up. The initial visual acuity improved from 20/120 to 20/30. Combination therapy with PDT and intravitreal bevacizumab appears to be effective in the treatment of CNV secondary to toxoplasma retinochoroiditis.


Discussion
The clinical features and the management of IOrFBs vary, depending on their size, location, velocity and composition. Unlike intraocular foreign bodies, sterile inorganic IOrFBs may be left in situ safely. [2] However, they can cause acute vision loss due to the associated intraocular trauma (globe rupture) or traumatic optic neuropathy or late complications, such as orbital cellulitis (especially if organic), inflammation (copper), systemic toxicity (lead), siderosis (iron) and discharging sinus (wooden). [3] Plastic, per se, is an inert polymer, but it caused devastating morbidity in our patient by virtue of its size and the temperature at the time of contact. The force of impact and the high temperature caused not only raised the IOP and, thus, intra-orbital pressure, leading to optic atrophy and also extensive thermal burns to the adnexal structures.
Severe thermal injuries of the eyes destroy the surface epithelia and cause ischemic necrosis and, later, contracture due to fibrosis. [4] In this case, the temperature of the foreign body at the time of entry was around 240 degrees Fahrenheit, causing third-degree thermal burns, resulting in sloughing and necrosis.
As the consequential tissue loss is not evident at presentation, these patients need to be counselled for the possible need for multiple surgeries later for cosmetic rehabilitation.
Reconstruction of the eyelids in our patient was started once the depth of the tissue damage due to burns became well demarcated. [5] The reconstructive surgery was undertaken in stages and the final result was cosmetically acceptable.
CT scan was the most useful imaging modality for localizing the IOrFB and delineating its posterior extent.
It also provided clues regarding the status of the globe and the optic nerve.
In conclusion, IOrFBs can cause significant ocular morbidity. Spreading awareness for the employment of protective measures in high-risk occupations should be made compulsory and would be helpful in reducing these injuries. [6] Intra-operative correction of corneal astigmatism was developed in the 1990s [1] but was considerably improved in the beginning of the past decade. [2] In order to achieve the desired outcome, accurate pre-operative data (axial length, keratometric data and accurate intraocular lens (IOL) power calculation with the use of the appropriate biometric formula) and proper surgical technique are required. All existing techniques are based on the fact that the IOL is implanted in the desired axis, as marked pre-operatively.
The growing use of the toric IOL in everyday clinical practice revealed the need for an accurate intra-operative IOL assessment procedure. [3] The aim of this paper is to present an intra-operative assessment method/procedure of accurate toric IOL implantation.

Materials and Methods
The patient's keratometric and topographic data were determined with the use of the Magellan Mapper (Nidek, Vigonza, Italy). Corneal topographic data were then inserted in the IOL manufacturer's software in order to obtain the axis of the desired astigmatic correction as well as the model and refractive power of the IOL. Afterwards, the 0-180 and the desired astigmatic axis correction were marked on the limbus with the use of the appropriate eye marker (Nujits Pre-Op toric reference marker with bubble-AE-2791TBL, ASICO LLC, Westmont, IL, USA) according to the manufacturer's instructions, with the patient sitting right before the beginning of the surgical procedure. The bubble ensured proper marking.
The surgical procedure was directly streamed and recorded in a computer in the anterior segment unit of our department. "Streamed pictures" is an alternative expression to describe the captured video frames. They provided (due to the availability of different time units and depending on the frame rate of the video recording) optimal conditions, such as angle of viewing and perpendicularity of IOL alignment, in order to calculate the IOL axis position and/or rotation. After sideport incisions and before the use of the viscoelastic, the desired astigmatic axis was marked in the limbus with the use of an Intra-Op toric axis marker, utilizing the acquired keratometric and topographic data and with the marked 0-180 axis as reference (AE-2792, ASICO LLC, Westmont, IL, USA).
After an uneventful IOL implantation, the viscoelastic was aspirated thoroughly and an air bubble was placed above the IOL (in order to maintain the IOL centered). The air bubble was then removed with the use of Balanced Salt Solution (BSS) infusion through the sideport. If, at this point, IOL implantation was considered by the surgeon to be perfect, a digital photograph was taken with a digital video camera and evaluated with the use of the following procedure. Medical personnel were responsible for the intra-operative toric IOL assessment. In the digital photograph, a protractor was superimposed on the IOL optic; its positioning was determined by the pre-operatively marked 0-180 axis on the eye and on the toric IOL axis (determined by three marks on each side-Screen Protractor, Iconico, v.4.0, Fig. 1). The assessor then evaluated the angle formed by the two above-mentioned axes in order to verify proper IOL implantation. The duration of this additional procedure was <30 s. The desired correction was not known to the assessor. Thus, bias was reduced. Immediate IOL axis evaluation was quite inconvenient to be performed by the surgeon because he/she operated under sterile conditions and could not operate a personal computer.
If IOL implantation was assessed to be inaccurate, the surgeon was advised to correct IOL positioning by rotating the IOL clockwise. The assessment procedure was repeated until accurate IOL positioning was achieved. It was essential to visualize the 0 and 180-degree mark and the reflection of the microscope lamp on the same corneal plane as well as to use streamed pictures of the surgical procedure and not just intra-operative digital photographs in order to achieve a perfect alignment of the above marks.
In a small case series (21 eyes), in one (5%) toric IOL (Alcon SN60T3) implantation there was an intra-operative deviation of 5 degrees recorded and corrected according to the procedure described above.

Discussion
Potential factors that may lead to inaccurate toric IOL implantation are incorrect marking of the 0-180 axis and relatively thick marking lines. Furthermore, IOL rotation is still possible following implantation.
A potential merit of our method may be the use of one instrument compared with two (Nuijts Toric axis marker, AE-2740 and Mendez Degree Gauge AE-2765) in the method proposed by Bauer et al. Furthermore, our proposed method may serve as an additional precaution measure for an accurate implantation assessment. A possible shortcoming of our assessment method may be the limitations of our instruments; the marker used employs a 10-degree step while the marker used by Bauer et al. employs a 5-degree step. [3] Moreover, the axis marker employed by our group does not permit easy intra-operative visualization and assessment of the final IOL axis. These limitations led to the development of an alternative assessment procedure.
The proposed assessment procedure may prolong IOL implantation by only a few minutes and may contribute to increased implantation accuracy in addition to intra-operative direct surgeon visualization because a standardized assessment method is employed. A potential shortcoming of this proposed procedure may be the cost of the video equipment required in order to obtain the streamed pictures. It is well established that every degree of misalignment results in a 3% reduction of astigmatic power in the IOL plane. [2,3] Thus, the magnitude of astigmatic error potentially introduced is dependent on cylinder power itself; the higher the cylinder power, the more accurate one needs to be. According to our experience (21 eyes) and with the use of the above-mentioned marker, the proposed procedure may serve as an additional precaution measure in order to avoid misalignments (especially in the case of higher cylinder powers) and may sufficiently assist in accurate toric IOL implantation as well as positioning assessment.

Pukhraj Rishi, Anusha Venkataraman, Ekta Rishi
A 14-year-old girl presenting with visual loss in both eyes was diagnosed to have healed toxoplasma retinochoroiditis in the right eye with active choroidal neovascularization (CNV) secondary to toxoplasmosis in the left. She underwent combination photodynamic therapy (PDT) and intravitreal bevacizumab as primary treatment. PDT was performed as per the 'Treatment of Age-related Macular Degeneration by Photodynamic therapy' study protocol and was followed by intravitreal bevacizumab after 2 days. CNV regressed at 8 weeks of follow-up and remained stable at 8 months of follow-up. The initial visual acuity improved from 20/120 to 20/30. Combination therapy with PDT and intravitreal bevacizumab appears to be effective in the treatment of CNV secondary to toxoplasma retinochoroiditis. Ocular toxoplasmosis is an important cause of choroidal neovascularization (CNV) in the pediatric age group. [1] The development of CNV adjacent to retinochoroidal scars is a well-known late complication contributing to loss of useful vision due to foveal involvement. Treatment modalities for CNV secondary to toxoplasma retinochoroiditis include laser photocoagulation, submacular surgery, photodynamic therapy (PDT) and anti-vascular endothelial growth factor (VEGF) agents. [1] We report a case of CNV secondary to ocular toxoplasmosis treated with a combination of verteporfin-PDT and intravitreal bevacizumab. Combination therapy for CNV secondary to toxoplasmosis has not been reported in the past.

Case Report
A 14-year-old girl presented with a 1-year history of deterioration of vision in both eyes. There were no significant ocular problems in the past. Medical and family history and systemic examination were unremarkable. On ocular examination, her best corrected visual acuity (BCVA) at presentation was CF 1 mt, N36 in the right eye and 20/120, N18 in the left eye. Biomicroscopic examination did not show any evidence of intra-ocular inflammation and the anterior segment was unremarkable in both eyes. Fundus evaluation of the right eye showed the presence of a punched-out pigmented lesion with well-demarcated borders at the macula that was suggestive of a healed toxoplasma lesion [ Fig. 1A]. Clinical findings were confirmed on fluorescein angiography [ Fig 1B] and Optical coherence tomography [ Fig 1C]. Left eye examination not only showed a punched-out pigmented lesion at the macula but also a choroidal neovascular membrane with adjacent subretinal fluid and hemorrhage just medial to the pigmented scar [ Fig. 2A].
The clinical findings were confirmed on fundus fluorescein angiography (FFA) and optical coherence tomography (OCT). The FFA of the left eye revealed an active subfoveal classic choroidal neovascular membrane with profuse leakage. Blocked choroidal fluorescence due to the overlying hemorrhage was also noted [ Fig. 2B]. OCT revealed subfoveal choroidal neovascular membrane (CNVM) and subretinal fluid adjacent to a subretinal scar [Fig. 2C]. The routine hemogram, kidney function tests and liver function tests were within the normal range. Mantoux test was negative and chest X-ray was normal. The anti-toxoplasma IgM titer was negative; IgG titer was however equivocal. A diagnosis of healed toxoplasma retinochoroiditis in the right eye and subfoveal CNVM secondary to toxoplasma retinochoroiditis in the left eye was arrived at. The nature of the disease and treatment options were explained. The patient underwent verteporfin-PDT as per the 'Treatment of Age-related Macular Degeneration by Photodynamic therapy' protocol. [2] This was followed by an intravitreal injection of bevacizumab (1.25 mg/0.05 ml) after 2 days.
At 8 weeks follow-up, the CNV showed regression with no evidence of subretinal fluid or hemorrhage on clinical examination or OCT. The BCVA improved to 20/30, N6 and the fundus remained stable up to the eighth month of followup [ Fig. 3]. No adverse ocular or systemic event related to the treatment procedure was encountered.

Discussion
The natural history of CNV secondary to toxoplasmosis reveals a poor visual prognosis. [3][4][5] The CNV originates adjacent to the retinochoroidal scars and leads to central visual loss due