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Utility of digitally assisted vitreoretinal surgery systems (DAVS) for high-volume vitreoretinal surgery centre: a pilot study
  1. Naresh Babu1,
  2. Piyush Kohli1,
  3. Soumya Jena1,
  4. Kim Ramasamy2
  1. 1 Vitreo-retinal services, Aravind Eye Hospital, Madurai, Tamil Nadu, India
  2. 2 Aravind Eye Care System, Madurai, Tamil Nadu, India
  1. Correspondence to Dr Piyush Kohli, Vitreo-retinal services, Aravind Eye Hospital, Madurai 625020, Tamil nadu, India; kohli119{at}gmail.com

Abstract

Aim To compare the surgical experience and preferred imaging platform, between digitally assisted vitreoretinal surgery systems (DAVS) and analogue microscope (AM), for performing various surgical manoeuvres.

Material and methods A questionnaire was used to evaluate the experience of surgeons who used DAVS for at least 6 months in the last 1 year.

Results Twenty-three surgeons, including 12 fellows, answered the questionnaire. Eighty-two per cent of surgeons got accustomed to DAVS in <10 surgeries. The higher magnification provided by DAVS was perceived as helpful by 87.0% surgeons. Seventy-eight per cent surgeons felt that DAVS provided a bigger field of view. Colours displayed on DAVS appeared unnatural to 39.1%. Difficulty using three-dimensional glasses over spectacles, asthenopia and dry eye symptoms while using DAVS were faced by 17.4%, 17.4% and 21.7% surgeons, respectively. Difficulty in frequent switching between DAVS and AM was faced by 30.4% surgeons. Difficulty in depth perception, hand–eye coordination and performance anxiety while using DAVS was faced by 43.5%, 21.7 % and 30.4 % surgeons, respectively. Majority consultants did not have any imaging platform preference for most posterior segment procedures, while majority fellows preferred DAVS. Majority surgeons preferred AM for anterior segment procedures and complicated situations like small pupil, corneal oedema and surgical surprise(s). Once the surgeons became accustomed to DAVS, none of them had to shift back to AM during any case.

Conclusion It was easy to adapt to DAVS. DAVS was preferred for performing most posterior segment surgeries. Drawbacks like unnatural colours of the projected image and difficulty in performing anterior segment manoeuvres need to be addressed.

  • imaging
  • macula
  • posterior chamber
  • retina
  • treatment surgery

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Summary statement

Surgeons, even the naïve ones, can perform various posterior segment manoeuvres with digitally-assisted vitreoretinal surgery system efficiently, easily and comfortably. Most surgeons feel that it will replace microscope for performing surgeries in near future.

Introduction

Ophthalmic surgeons are prone to chronic neck and back problems due to the awkward posture acquired while using the microscope binoculars to perform surgeries. The problem is especially severe in the vitreoretinal (VR) surgeons, who perform long duration surgeries.1–5 The recently developed three dimensional (3D) viewing systems allow the surgeons to operate in a ‘heads-up’ position. This position is said to be more physiological, and short-term studies have shown it to alleviate the physical stress sustained by surgeons on their back and neck.6–12

These systems have been shown to provide superior ergonomics along with good image quality and are a better teaching tool than the analogue microscope (AM).6–12 However, all these studies were based on the experience of either a single senior surgeon or volunteers performing non-clinical tasks.6–12 The user-friendly nature of these systems can be established by evaluating the experience of both senior as well as junior surgeons performing actual surgeries.

In this pilot study, we report the initial 1 year experience of 23 junior and senior surgeons regarding the intricacies of performing various posterior segment surgeries on both the platforms, comparing the stepwise surgical experience and the preferred imaging platform for performing various surgical manoeuvres between digitally assisted vitreoretinal surgery systems (DAVS) and AM.

Material and methods

This retrospective trial was conducted at two centres of Aravind Eye Hospital, India (Madurai and Coimbatore), after taking approval from the Institutional Review Board. The study adheres with the tenets of the Declaration of Helsinki. None of the authors have any financial interests.

The surgical microscope and wide-angle viewing system used for the study were OPMI Lumera T and RESIGHT 500 (ZEISS, Oberkochen, Germany), respectively. The DAVS used was NGENUITY 3D Visualization System. This DAVS is being marketed by Alcon (Forth Worth, Texas, USA) in collaboration with TrueVision Visualization System (Santa Barbara, California, USA). In the system, a high-dynamic range camera is positioned in place of the microscope’s eyepiece. The camera is connected to a central processing unit, which processes the live images and converts them into three-dimensional (3D) format and displays them on a 55-inch LED monitor. The surgeon views the screen using a pair of passive polarised 3D glasses. All the surgeries were performed with Constellation vitreoretinal surgical system (Alcon).

As per the usual protocol followed at our institution, around 20–30 surgeries are performed in a day. These surgeries are performed by two or more consultants along with one or two fellows. The fellows perform various surgical steps under the guidance of the consultants present in the operating room (OR). Both the systems are randomly used by all the surgeons depending on the availability of the systems. As the cases were randomly performed on either system depending on system’s availability and not on the nature of the cases, there was no case selection bias. The surgeries done included combined mechanism retinal detachment, dropped nucleus, endophthalmitis, epiretinal membrane, full-thickness macular hole (FTMH), macular tractional retinal detachments, rhegmatogenous retinal detachment, scleral-fixated intraocular lens (SFIOL), silicon oil removal and vitreous haemorrhage (VH).

The experience of all the surgeons who had used the DAVS for at least 6 months in the last 1 year was evaluated with the help of a questionnaire. The questionnaire had multiple choice-based questions. It was adapted from the previous published studies and modified to evaluate the surgeons’ experience while operating with DAVS and AM in different clinical situations. The surgeons were questioned regarding the transit period to shift from AM to DAVS, that is, number of surgeries they took to get accustomed or comfortable while operating with DAVS, regarding advantages and disadvantages as well as the preferred modality for performing various surgical manoeuvres. The questionnaire was created with the help of two highly experienced surgeons (NB and KR), both of whom have more than 15 years’ experience of performing VR surgeries for various pathologies. The questionnaires did not mention the name of the respondent and were compiled by the statistics department of the hospital in order to prevent any sort of bias. The response of the questionnaire was further correlated with the experience of the surgeons.

Statistics

Statistical analysis was performed with STATA statistical software, VV.14.0. The categorical variables were presented as frequencies and percentages.

Results

Twenty-three surgeons answered the questionnaire, out of which 12 were currently undergoing fellowship. Among the consultants, four, two, three and two had a postfellowship experience of <2, 2–5, >5–10 and >10 years and had operated around 75–100, 150–200, 300–500 and 500–1000 posterior segment surgeries on DAVS. The fellows had performed around 25–50 posterior segment surgeries on DAVS. Seven (63.6%), one (9.1%) and two (18.2%) consultants took <5, 5–10 and 15–20 surgeries, respectively, to get accustomed to DAVS. One (9.1%) consultant, with a postfellowship experience of 2–5 years, could not get accustomed to DAVS even after 1 year and preferred using AM whenever possible. However, among the fellows, five (41.7%), six (50.0%) and one (8.3%) surgeons took <5, 5–10 and 10–15 surgeries, respectively, to get accustomed to DAVS.

All the surgeons felt that DAVS provided higher magnification compared with AM. The magnified view provided by DAVS was perceived as helpful by 87.0% (n=21/23) surgeons, while one fellow found it to problematic. Seventy-eight per cent (n=18/23) surgeons felt that DAVS provided a bigger the field of view, while one consultant thought that AM provided a bigger view. The colours displayed by DAVS appeared unnatural to 39.1% (n=9/23) surgeons. Seventeen per cent (n=4/23) surgeons felt that they could not obtain high-quality image on DAVS, even after white balancing. Difficulty in depth perception while using AM and DAVS was felt by zero and 36.4% (n=4/11) consultants, and 16.7% (n=2/11) and 50.0% (n=6/12) fellows, respectively. Difficulty in hand–eye coordination while using AM and DAVS was felt by zero and 9.1% (n=1/11) consultants, and 16.7% (n=2/11) and 33.3% (n=4/12) fellows, respectively. Performance anxiety while using DAVS was felt by 30.4% (n=7/23) surgeons. Difficulty in frequent switching between DAVS and AM was faced by 30.4% (n=7/23) surgeons (table 1). All the consultants felt more comfortable in assisting fellows while the fellows operated on DAVS rather than AM. All the fellows felt more comfortable while observing surgery on DAVS rather than AM.

Table 1

Response for questionnaire regarding the experience of surgical performance using DAVS and AM

Back or neck problem are usually faced by 43.5% (n=10/23) surgeons at the end of the day. After using DAVS, 56.5% (n=13/23) surgeons felt that such pains were lesser compared with AM, while the rest felt that the pains were similar. None of the surgeons felt that using DAVS caused more pains. Asthenopia and dry eye symptoms while using DAVS were faced by 21.7% (n=5/23) and 17.4% (n=4/23) surgeons, respectively. Asthenopia and dry eye symptoms while using AM were faced by 17.4% (n=4/23) and 21.7% (n=5/23) surgeons, respectively. Only 17.4% (n=4/23) surgeons had difficulty using 3D glasses over spectacles (table 1).

Difficulty in changing from PS to AS while using AM and DAVS was felt by 18.2% (n=2/11) and 36.4% (n=4/11) consultants, and 50.0% (n=6/12) and 83.3% (n=10/12) fellows, respectively. Seventy-three per cent (n=17/23) surgeons felt that the OR looked crowded due to the presence of the big DAVS screen. Surgical videos were edited using DAVS by 56.5% (n=13/23) surgeons, out of which 92.3% (n=12/13) found the software to be user-friendly (table 1).

Most consultants did not have any imaging platform preference for posterior segment surgical steps like PVD induction (63.6%), base dissection (45.4%), endolaser (66.7%), working under air (54.5%), working with chandelier (50.0%) and ILM peeling (45.4%). However, most consultants preferred AM for TRD cases (45.4%). On the contrary, most fellows preferred DAVS for posterior segment surgical steps like PVD induction (45.4%), base dissection (58.3%), endolaser (81.8%), working under air (72.7%), working with chandelier (85.7%) and TRD (55.6%). However, most fellows preferred AM for ILM peeling (83.3%) (table 2). After the surgeons became accustomed to DAVS, none of them had to shift back to AM for performing any particular surgery manoeuvre.

Table 2

Response for questionnaire regarding the choice of DAVS or AM for particular surgical manoeuvres

Most surgeons preferred AM over DAVS for anterior segment procedures like SB (95.0%), constructing a scleral tunnel (86.4%), SFIOL (100.0%), suturing scleral tunnel (60.9%) and scleral ports (56.5%), and corneal tear suturing (72.2%). Similarly, most surgeons preferred AM over DAVS for operating patients with special conditions like small pupil (43.8%) and corneal oedema due to cataract surgery (43.8%) and dealing with surgical surprises (52.2%) like intraoperative lens touch or posterior segment bleeding (table 2). Only senior consultants had performed complicated surgeries like PPV with glaucoma drainage device (GDD) or penetrating keratoplasty (PKP) with SFIOL. AM was preferred over DAVS by 75.0% (n=3/4) and 60.0% (n=3/5) surgeons for GDD and PKP, respectively.

Sixty-three per cent (n=7/11) consultants said that they would prefer AM, while 66.7% (n=8/12) fellows said that they would prefer to use DAVS in a high-volume VR centre. Sixty per cent (n=14/23) surgeons thought that DAVS will replace AM for performing posterior segment surgeries in near future (table 1). The one surgeon who could not get accustomed to DAVS felt that this was because of the unnatural colours of the projected images, inability to make out finer details of retina and increased aberration in the periphery of screen.

Discussion

In the current era of technology revolution, newer innovations are rapidly changing the methods of practise and phasing out the older equipments. One of the latest additions in ophthalmic imaging is the DAVS. The superior ergonomics offered by the machine is attracting the attention of a number of surgeons. However, for any technology to become popular, it should be user-friendly for both the experienced and the naïve.

Few authors have objectively measured the depth of field and resolution of provided by DAVS. Eckardt et al 7 found that depth of field, resolution, zooming and focusing capabilities, speed and ease of operation were similar with both the platforms. Also, they compared the performance of 20 volunteers in performing meticulous non-surgical tasks. The volunteers made lesser errors using DAVS and considered it to be more comfortable.7 Freeman et al 13 found that DAVS provided higher resolution than AM at all the magnifications and higher depth of field only at 5× magnification, while depth of field at 13× and 18× magnification was similar for both the platforms.

We evaluated the experience of 23 surgeons, which included fellows, junior and senior consultants with varying degree of surgical experience. All the surgeons had performed sufficient number of surgeries on DAVS. More than 80% of the surgeons got accustomed to DAVS in <10 surgeries. Even the fellows with little experience with VR surgery adapted very quickly to the platform. In fact, the younger generation is expected to pick-up the technology faster as it is already exposed to the 3D technology in form of video games. The senior surgeons, who have lost their power of accommodation, also find it comfortable to use as they can relax their accommodation and comfortably view the screen kept few feet away. Eckardt et al also reported that after <10 surgeries, the surgeons could perform various manoeuvres easily.7 The major advantage provided by DAVS is the bigger field of view provided at higher magnification compared with AM. More than three-fourth surgeons in our study felt that DAVS provided a bigger field of view. Palácios et al 14 reported that the surgeons in their study found that DAVS provided a bigger field of view at a higher magnification with an accurate focus. Major concern with DAVS are difficulty in attaining hand–eye coordination and depth perception, asthenopia and dry eye symptoms caused by constant viewing of 3D screen.15–19 Around 20% surgeons faced difficulty with hand–eye coordination with DAVS, compared with 10% with AM. Around 40% surgeons faced difficulty in depth perception while using DAVS, compared with 10% with AM. Both these difficulties were higher among fellows than consultants. Less than 20% surgeons in our study experienced asthenopia and dry eye symptoms. This incidence was similar to that experienced with AM. Other authors have also reported that surgeons rarely experienced these symptoms.7 8 20 Only 30% surgeons faced difficulty due to frequent change of platform from AM to DAVS and vice versa.

Back and neck problem is a major problem among the VR surgeons.2–5 With the use of DAVS, more than half of the surgeons felt that pains were lesser. Other authors have also reported the incidence of neck and back pain reduced greatly after heads-up surgery.7 8 20 21 This was because DAVS allowed the surgeon to operate in a posture with back well supported, in contrast to constant stooping posture attained to look through the eyepieces. There have been concerns regarding increase in neck pain while using DAVS due to lateral placement of the monitor.14 22 However, none of the surgeons in our study raised such a concern. This may be because the discomfort caused due to lateral viewing was less than caused by the stooping posture. Although the incidence of neck and back pain may increase with long-term use of DAVS, early results are favourable. While using DAVS, the surgeons did not have to worry about fogging of eyepiece and constant adjustment of the height and interpupillary distance of the eyepiece, especially during the change of surgeon. However, switching of the image invertor with the help of a keyboard and adjusting screen–doctor distance had to be done frequently. Overall, there was a higher need for an additional unscrubbed person in the OR while using DAVS than AM. Another problem with DAVS is that if anything goes wrong with the system, it is impossible to convert to AM in case backup of microscope is not available. In our OR, both the systems are available, and the system can be changed back to AM within few minutes in case of any problem.

Nearly 40% surgeons felt that the colours displayed by DAVS were not natural, and the images have a reddish hue. This is especially problematic in case of a sudden bleed for example while treating TRDs, as the clarity suddenly decreases. Eckardt et al 7 reported an increase in image noise in cases with a dense VH. However, none of the surgeons in our study had to switch back to AM for any case. Similarly, Eckardt et al also reported that they did not have to make any such switches.7 Rizzo et al 21 reported that due to bad visualisation, they had to revert back to AM in 1 out of 200 cases. Palácios et al 14 reported that image resolution in case of surgery for FTMH was poorer with DAVS compared with AM. However, none of the surgeons in our study stated such a problem.

One of the advantages of DAVS is its better educational value than AM. The consultants felt more comfortable in assisting fellows while the fellows operated on DAVS rather than AM. Also, the fellows felt more comfortable while observing surgery on DAVS rather than AM. This was because DAVS enables the bystanders to have exactly the same view as the surgeon while they can maintain their normal posture. With DAVS, consultants do not need to stand beside the microscope but can rather sit at a distance and guide with the help of bluetooth ear phone. The assistant nurses also perform better as they get a 3D view of surgery and can predict the surgeon’s instrument requirements especially in case of a complication. Rizzo et al found a very high satisfaction score when the OR nurses were questioned for their comfort.21 Other advantages include the need of lesser endoillumination intensity, thus reducing retinal phototoxicity and the inbuilt user-friendly video editing software.8

Most consultants did not have any imaging platform priority while performing posterior segment surgeries, while the fellows preferred DAVS. This was because although the consultants found DAVS more comfortable, they had already got used to AM and were a bit sceptical against the new technology. Palácios et al also concluded that although surgeons initially favoured AM due to inertia, they were slowly switching over to DAVS without difficulty.14 22 On the contrary, the fellows had just started operating and found DAVS much easier and fascinating to use. The only exceptions were TRD and ILM peeling, where majority of the surgeons preferred AM over DAVS. AM was preferred over DAVS for TRDs because of the expected bleeding that causes a decrease in image quality displayed by DAVS. Similarly, AM was preferred over DAVS for ILM peeling because the surgeons felt that performing very fine manoeuvres was easier with AM. Zhang et al reported an increased incidence of nausea and vomiting among surgeons while performing prolonged endolaser.20 However, no surgeon in our study noted such a problem.

For performing anterior segment procedures, majority of the surgeons preferred AM. Palácios et al 22 also reported that the surgeons were facing difficulties in performing anterior segment manoeuvres and had a longer adaptation time. Similarly, AM was the preferred platform for operating patients with special conditions like small pupil, corneal oedema due to cataract surgery and surgical surprises like intraoperative lens touch. Zhang et al also reported that a greater difficulty was felt with DAVS than AM when operating on patient with media opacities.21 The preference to use AM for complicated situations in our opinion is due to the fact that the surgeons have higher experience in dealing with complicated cases using AM, and they do not want to take a chance in such cases.

With overall experience, majority of consultants in our pilot study said that they would prefer AM, while majority of fellows said that they would prefer to use DAVS in a high-volume VR centre. We believe that this was simply because the consultants started their surgery on AM and were sceptical to switch to the new technology. On the contrary, fellows started learning the surgeries on the 3D system itself and did not face any difficulty. Majority surgeons in this study felt that DAVS will replace AM for performing posterior segment surgeries in the near future as DAVS provides better ergonomics with good image quality. Although majority surgeons preferred AM while operating complicated cases, with increasing experience, surgeons will start using DAVS for complicated surgeries as well.

DAVS has few drawbacks like unnatural colours of the projected image, difficulty in inverting the image when changing from posterior-to-anterior segment and difficulty in performing anterior segment manoeuvres. These issues need to be addressed before it gains mass acceptance. The makers of the machine are planning to improve the quality of white balancing and introducing a special mode for operating VH and a footswitch for switching the image invertor (Patrick Wolf, Leica Microsystems, oral communication, 31 August 2018). Further innovations need to be made to make visualisation in hazy medium and small pupil better.

To the best of our knowledge, there have been no previous studies comparing the surgical experience and surgeons’ preference for performing the various posterior segment surgical manoeuvres using the two imaging modalities. The strengths of our study were a detailed questionnaire evaluating the surgeons’ experience regarding all the steps and surgeries that a VR surgeon needs to perform as well as evaluation of response from fellows to senior consultants with more than 15 years of experience. Our pilot series showed that the transition from traditional microscope to the heads-up technique can be made in a remarkably short time. However, further innovations are needed to make it mainstream.

References

Footnotes

  • Contributors NB, SJ and KR: conception and design, critical revision of manuscript, final approval of the version published and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. PK: conception and design, data acquisition, data analysis, drafting manuscript, critical revision of manuscript, final approval of the version published and agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

  • Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data sharing statement Data are available in a public, open access repository.

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